If you have a few hours this weekend, you can build this automatic Foursquare check-in system yourself, with very little upfront investment. If the idea sounds appealing, but you're not sure if you have the skills needed to make this happen, don't worry - the hardware may soon be available for purchase alongside re-modded sensors that dangle on your keychain.

Materials

To get started, you'll need the following materials:

• A Nike+ sensor: If you don't already have a Nike+ sensor, you can pick one up by locating the nearest store that sells Nike gear using the company website. Sensors are sold either with a pair of running shoes or along with the Nike+ sportsband. (If you don't have a sensor on hand, you can still do this. Stumble.to's service can register Wi-Fi clients via MAC addresses, too.)
• A USB+iPod Serial Adapter: This $25 breakout board (available here from Sparkfun Electronics) sends and receives commands to the receiver and listens for individual foot pods. Your local electronics hobbyist shop may carry something similar.
• A computer

Accounts

• Obviously, you'll need a Foursquare account. (Twitter check-ins and Fire Eagle are also supported.)
• Secondly, you need to register an account with Stumble.to and obtain an API key.

Software

• Python
• PySerial
• The shoe-agent Python script (direct download): This is the script that connects the Nike+ sensor to the Stumble.to software.

Just Do It!

Once you have all the components in place, here's how to get started:

1. Install Python and PySerial
2. Plug in the serial adapter.
3. Obtain your API key from Stumble.to
4. Edit the shoe-agent script with your API key information and specify the serial port your USB adapter appears as.

That's it! Halverson is working on a more detailed how-to guide, so stay tuned to his blog for an update on that, if you need further details. (Update: Here it is!)

Garage Project to Become Commercial Success?

Although the above guide is meant for electronic hobbyists who want to have a little fun with Foursquare and hardware sensors, this DIY "garage project" may end up leading to commercial success for those invovled. Halverson says he's thinking now about how he could build a different type of sensor, like one that hangs on your keychain, for example, instead one that sits in your shoe or pocket. The new sensor could be thinner and lighter or maybe have an on and off switch that would register your check-ins automatically when on while still allowing an easy way to go off the grid when needed.

The Stumble.to Web service created by Eric Butler and Ian Gallagher has incredible potential as well. Although it only works with Foursquare, Fire Eagle and Twitter for the moment, additional services like Facebook Places, Gowalla and other check in-based social networks can and will be added in the future. Stumble.to essentially works as a middleman between hardware devices and location-based networks. It works with sensors, but also with Wi-Fi clients like laptops and smartphones that register their MAC addresses with the service.

Bringing Check-Ins to Non-Smartphone Users with Low-Cost Sensors

In reality, this project isn't all that different from the system created by mobile check-in service Shopkick, but with cross-platform appeal. Shopkick, now available as a mobile application for smartphones, offers deals to users who check in at popular retail establishments like Best Buy and Macy's. However, it forces the venue to install the company's proprietary hardware to verify that the check-ins come from people who are actually in the store. It also requires a smartphone.

Using low-cost components at the venue level and short-range sensors like the one from Nike+ offers the same benefits but without excluding users who prefer using other location-based services... or even those who don't own smartphones! A sensor combined with an online account at Facebook, Foursquare or another site could engage feature phone users who want to participate in this hot, new check-in game, but can't install mobile applications on their phone.

For the end user, the experience could be simple: it would only be a matter of registering an account with Stumble.to and associating their preferred services with their keychain sensor. Afterwards, they could continue to enjoy the features of location-based apps, like the discounts, mobile coupons, tips, reviews and other rewards, without having to actually having to perform a manual check-in on their phone.

Another interesting side note: Stumble.to has a "check out" feature too, meaning it can calculate the time you spend at a venue. Although no location-based service tracks this metric today, it could be implemented in future iterations to discourage the so-called drive-by check-ins (those where the user checks in as they pass a venue, often while driving, in order to get the points or rewards in a given location-based game like Foursquare). A service could perhaps dole out more points or better rewards to those who actually stayed put for awhile instead of those who were just cruising by.

What Do You Think?

Whether you geek out on the DIY project or want to wait for a commercially available system, you can see there are clear advantages to automated, hardware-based check-in services. Whether or not companies like Foursquare, Gowalla, Brightkite and others will actually want users to skip using their apps in favor of automation is another matter entirely, though. Some smaller services may be dependent on in-app ads for example, or links posted by their users that drive traffic to company homepages. Automation would have an effect on how the services could be effectively monetized, and that's something they will need to consider thoughtfully before embracing a system like this.

But that's just them. We think it's awesome - what about you?

When you click the "Get Started" button in the Friends on Fire Facebook application, you're redirected to Yahoo's Fire Eagle page where you have to sign in with a Yahoo ID. If you don't already have one, then you'll need to create one here - an extra step that may be a bit off-putting for new users.

Once you've signed in, you must provide an email address for receiving important updates from Fire Eagle. You then must also specify at what intervals you want to receive an email that asks if you're still comfortable sharing your location. The choices you're given are "once per month," "once every 3 months," and "don't bother." Finally, you have to accept the terms of service and give the Facebook app access to your location.

Back in Facebook, you'll be shown the other Fire Eagle users among your friends and given the opportunity to connect with them. You can also configure additional settings like how exact the location updates are, who can see them on the map, and whether or not the posts update your wall.

Mobile Updaters

Of course, if you're out and about, you're not necessarily going to be hauling around your computer with you. Instead, you'll want to grab one of the mobile Fire Eagle updaters from Yahoo's Gallery. These apps include simple mobile updaters like Fire Fone for the iPhone as well as more robust social networking apps like Brightkite. However, even though these apps are integrated with Fire Eagle, we had some problems getting one of them to also update the Facebook Fire Eagle map. Our preferred mobile social network Brighkite, for instance, updated our Wall but the Fire Eagle map did not show our location.

According to Tom Coates, the head of the Fire Eagle project, it might take a couple of minutes for your location to show up when you use a third party application, but we've waited for 20 minutes so far and the Brightkite update never made its way to the map. Obviously, this delay could hamper the usefulness of a location-aware app - especially if you're checking in at places you're only going to be for a short while - like the local coffee shop or a restaurant where you stopped for lunch.

There are several apps in the list to try, so it looks like we'll need to check them one-by-one to see if that's a common issue, or something specifically related to Brightkite. (Share your experiences in the comments!)

Fire Eagle Updater for Firefox

The Fire Eagle Firefox add-on is much simpler to use. After installing the extension, you only need to click a button in your browser toolbar to update your location. This is useful for those scenarios when you are, in fact, toting your laptop around. It's easy to imagine college students using this on campus, traveling business executives checking in as they launch their browsers in airports and hotel rooms, or web workers checking in from their favorite Wi-Fi hotspots.

Both the add-on and the new Facebook application will help push the concept of location-awareness even further into the mainstream. Although, as we mentioned yesterday, the next step after location-aware apps may be location-aware ads. However, we're still excited to see the developments taking place in this area, especially when it comes from a standards-based platform with strong privacy controls like Yahoo's Fire Eagle.

However, it is important to note that Yahoo has made privacy a central focus of the platform and right upon sign-up, users are given the option to receive regular emails from Yahoo to see if they are still comfortable with sharing this kind of information. If you do not respond to this email, Yahoo will automatically disable your Fire Eagle account. Yahoo also allows users to turn the service off when they want to keep their location private.

Upon launch, Fire Eagle seems to be having some trouble with keeping up with the sudden rush of new users, as the service was sometimes unable to pinpoint our location. Once it is running smoothly again, we would not be surprised if Fire Eagle could make good on its promise of becoming the central clearinghouse for location services. Already, close to 800 developers are working on applications that make use of Fire Eagle in some form or another.

The first two apps to engage with Fire Eagle is Dopplr, the super-hip social-travel app, and Danger Day, a service for updating your location on Twitter. Others are ramping up quickly, though Fire Eagle is still invite-only. We've got invite URLs posted at the end of this post, knock yourselves out. The Yahoo! Group for developers interested in Fire Eagle is here.

First, Yahoo! put privacy right out front. Many people want their data to be portable from service to service and many people want that to include their location data from mobile or other interfaces. I personally don't want my location broadcast automatically, at all, to anyone thank you very much. Fire Eagle has privacy and user control of data written all over it.

Users have the option to hide themselves with a single click, they can click to purge all their data from the Fire Eagle databases, the service even lets you select how often you'd like to receive an email reminding you that it is tracking your location as asking you to confirm that you want tracking to continue. By default you're emailed once a month for consent to be reconfirmed! Hello trust building measures! It's almost enough to make me interested in exposing my location, selectively.

Second, the way Yahoo! is developing its Platform is great. It's offering API kits in five different programming languages, it's got user authorization protocols already available for web, desktop and mobile apps and it's using the open standards community built oAuth to facilitate faster, more secure mashups. We wrote about oAuth's launch here and Google is also using it extensively in OpenSocial. This aint no cry-baby do it my way or I'm taking my ball and going home framework like the Facebook platform. This is leveraging universal open standards.

Standards based platform plus strong privacy equals the best scenario I can imagine for a location tracking service. We'll see what kinds of innovative applications get built on top of it.