ReadWriteWeb

For music fans, all-you-can-stream music services like Spotify, Rhapsody, MOG and Rdio are kind of dream come true. Signing up gives you instant access to a library of millions of songs from major label and indie acts from around the world. Most services are now free, with some limitations on usage. For paying users, as long as you keep your subscription, there's really no need to pay for most individual tracks or albums (unless you're an audiophile). In the case of Spotify, you can even merge your local music collection with the service's cloud-based selection of music. Awesome.

For artists, it's another story. The dirty little secret of services like Spotify and others is that they are not particularly lucrative for artists. At all. Each of them has managed to court record labels with attractive enough licensing deals, but that doesn't necessarily trickle down to the artists themselves. As a result, many artists have held back new releases from streaming services, or jumped ship all together.

When Spotify first launched in the U.S. over the summer, few doubted that the service would be popular among music fans. The real question has always been whether the company's freemium business model would manage to convert enough users to paying subscribers. It's still relatively early, but so far things look promising.

More than 3 million people are now paying to use Spotify, according to the Financial Times. That's a conversion rate of more than 20%, a figure that has reportedly increased by 5% since the service hit 1 million users last year. In other words, not only is Spotify itself growing, but the rate at which people sign up for a premium or unlimited account is also increasing.

In 2011, we collectively listened to 64,876,491,602 songs on the Internet. Whether it was on YouTube, SoundCloud, Rdio or MySpace, the citizens of the Web listened to quite a lot of music last year. Bands and musicians made over 3 billion new fans, who viewed artist profiles over 16 billion times. These are just a few data points recently released by Next Big Sound, a startup that tracks the popularity of music and individual artists across a range of digital music providers and social services.

Digital music only continues to grow and mature, as streaming services explode, Internet radio companies go public and developers begin using the power of open APIs to mash up sounds and services. SoundCloud alone saw 231% growth last year, while Twitter saw a 104% increase in music-related activity.

Spotify was essential to Facebook's frictionless sharing plan. But not every app is down for cluttering news feeds with moment-to-moment information about what its users are doing, saying, thinking and listening to.

Music streaming service Pandora, for one, is staying out of Facebook's social apps completely. "It's true that music is a social experience, but it's also a very private experience," Pandora founder Tim Westergren recently told CNN. "We have to be very cautious."

Surprise! You know that free, unlimited Spotify account you eagerly signed up for when the service first launched in the U.S. over the summer? That was a six-month trial, in case you missed it in the fine print. Next week will mark the half-year anniversary of Spotify's long-awaited U.S., which means that those who were first in line to get a free account will start to see limitations fall into place.

Spotify's free accounts are normally restricted to ten listening hours per month. If you really, truly love a particular song, you'll only be able to stream it five times in a given month. These caps will come on top of the usual limitations of free accounts: You have to listen to advertisements and there's no mobile access.

For the last few years, many everyday folks who've been asked in surveys, "What is a cloud application?" have either guessed wrong or said they don't know. Folks don't know what "the cloud" is, and for the most part, that's not their fault. Unlike the Internet, which truly is a single network of interconnected resources, "the cloud" is more of a concept, one which can be leveraged by marketing departments to mean just about anything.

For this year's ReadWriteWeb list of the most important and influential consumer-grade cloud computing apps of the year 2011, we focused our gaze on services that truly fit the formal definition: specifically, services that 1) utilize a remote resource of 2) variable capacity 3) which the user can provision for herself, 4) which is mostly or totally independent of programs installed on the user's devices or PCs, and 5) which is not just a Web site with a big server. You may have seen Facebook on some publications' Top Cloud lists already; by our definition, Facebook is not a cloud service. But we did look for providers that perform innovative, discrete functions built around their services.

In the fast-changing digital music streaming space, it's hard to know which service is best for you. Spotify gets the most hype, but lots of people love Rdio, which has solid backing and a huge library of music. There are also beloved underdogs like MOG and Grooveshark.

When it comes to choosing which option to go for, the most you can do is take each service for a spin, run a couple searches for stuff you like and see what comes up. You can get a general feeling of which one's a better fit and go with your gut, but wouldn't some hard data be nice?

Normally when a tech company launches a product or feature that's billed as a potential "killer" of a popular incumbent, there's cause to be skeptical. Quite often, that's just unsubstantiated hype either on the part of the company itself or tech writers.

In the case of Spotify's new Web radio feature, we're not going to go so far as to say that it's a "Pandora killer," but its inclusion in Spotify's desktop client is going to give the up-and-coming streaming service a tangible advantage over the 11-year-old Web radio service.

This week, darling of the all-you-can-stream music space Spotify announced that it's opening up to third party developers and creating a platform on which they can build HTML5 apps to run within its desktop client. Once approved by Spotify, those apps will be available to users from the service's new "App Finder" button. They've also added a new home screen that show's what music is trending among one's friends, as well as an improved social experience all around.

The new features are not yet included in the Spotify desktop client, but curious users can download a preview of the next version of the software. We did and after using it, we're finding that the inclusion of third party apps makes Spotify much better.

I'll never forget when I first discovered Napster. I was in high school and had heard about it from a friend. As an avid music fan, I was delighted to suddenly find myself with access to a seemingly limitless trove of songs, some of which were previously available only on $40 CD-R bootlegs in the back of record shops where they also sold paraphernalia strictly designed for smoking tobacco and only tobacco.

I never abandoned purchasing music all together, but the MP3 struck me as a far more convenient format than the compact disc, and Napster gave me quick and easy access to a world of MP3's. When Radiohead's "Kid A" showed up on Napster weeks before the CD was available in stores, what was I supposed to do? Ignore it?