But in terms of usage, Google is far ahead of the pack - 1114 Mashups use a Google API. It is also interesting to note that even though Microsoft has 3 times the APIs of eBay, they both have the same number of Mashups using their APIs.

Also check out the mashup matrix, which gives insights as to how APIs cluster with each other. Each dot in the matrix implies that two APIs are part of the same mashup. One way to interpret the matrix is that a cluster of dots indicates logical belongings of APIs, or a natural fit with each other. 

Analyzing Mashups: Mapping continues to dominate

The Mashup dashboard on ProgrammableWeb contains a lot of interesting statistics about Mashups. On the right, we see the numbers for the past six months. We conclude that mashups have been growing steadily, but not spectacularly. This is not surprising, because creating mashups requires time and more importantly technical know-how.

The figure below shows the distribution of tags for mashups. This is calculated by analyzing the tags across all the mashups posted onto ProgrammableWeb. Mapping is overwhelmingly the most popular category, spanning 43% of all mashups. This is not surprising because it all started with the Google Maps API - and people are still very excited about putting information on a map. Photos, Search and Shopping tags are roughly equal - with 10% each.

Mashup popularity

ProgrammableWeb currently measures popularity by number of views. This is a bit unfortunate, particularly because there is no way to sort mashups by rating. As a result, the most popular mashup - Virtual Places - is one that does not have a high rating. It looks interesting and claims to be sophisticated, but it did not load for me. The second most popular mashup was called Wii Seeker. As the name implies, it helps people find nearby locations that have a Nintendo Wii. It must have been really popular at some point, but now it looks fairly primitive. The next mashup that caught my attention was the one in fourth place called Weather Bonk. This one had a high user rating and was actually very interesting, as it pulled together live weather, historical information, forecasts and web cameras.

Using Delexa for mashup popularity

Next we briefly leave ProgrammableWeb and head over to Delexa, a mashup site that uses del.icio.us and Alexa APIs to show the most popular sites by category. The top mashup tagged by del.icio.us users was Housing Maps, a classic mashup that combines Google Maps and Craigslist to help people find housing.

The second most popular mashup according to Delexa was GeoGreeting, which is more entertaining than useful. This mashup showed geographical locations with buildings that resembled the shape of the letter that you typed. The third most popular mashup according to Delexa was Weather Bonk, the same one that caught my eye on ProgrammableWeb.

Analyzing APIs: GoogleMaps used in 50% of mashups

Back now on ProgrammableWeb and the chart on the right demonstrates the growth of APIs. As with mashups, the actual growth is not that impressive - but it is steady. As of now, there are close to 400 registered APIs. The way that Programmable Web measures API popularity seems to be more objective and reliable than is the case with mashups. The popularity equals the number of mashups that use the API and the chart below shows the distribution of the most popular APIs:

There are few surprises in this information. Google Maps is by far the most popular API, with 50% of mashups using it. Flickr and Amazon are next with 11% and 8% respectively. Also, it's notable that 5% of mashups are using YouTube - which probably corresponds to the recent rise of video aggregators like Vidmeter. Finally, 4% and total of 74 mashups use the del.icio.us API. 

One API that caught my eye was Cloudalicious, which shows the distribution of tags for a particular URL over time. This can be insightful in terms of understanding how people's perception about your site is changing (or not). Check out the del.icio.us tag cloud trend for Read/WriteWeb:

Conclusion

What can we derive from this analysis? It appears that mashups are certainly cool, but they are not burgeoning. The growth has been steady, but not really explosive. This begs the question: why? 

There are several reasons, the primary one being that most current mashups are created for fun and not for business. Enthusiasts with some spare time on their hands are building these during their evenings and weekends, without having monetization in mind. The second reason is that APIs, as with any software libraries, have a learning curve. Certainly Internet companies are trying to expose their services in the simplest possible way, but not everything can be made simple.

Is this what mashups will be - a playground for enthusiasts? I believe that the answer is 'yes'. Even though services like Yahoo! Pipes, Teqlo and Dapper are working to simplify the process of creating mashups, it will likely remain a fairly technical exercise done by enthusiasts. 

However, it is also likely that we will see companies and products taking ideas from many mashups and creating applications with the combined functionality. For example, taking ideas from the best mashups (like Cloudalicious) and creating a set of tools for bloggers and marketers would be very useful. So mashups will, I think, become the labs of the web - where rapid prototyping is done by enthusiasts, which gives rise to more integrated offerings by web companies.

Please let us know what your favorite mashup is and give us your take on where mashups are heading.