The Echo Nest API, a suite of web services for music search and recommendations, officially launched at DEMOfall08. As they say: " Input any song and get an XML description of its content." It's a very intriguing API that's increasingly attracting the notice of the developer community. Paul Lamere exemplifies the excitement Echo Nest is eliciting in his recent Sun blogs post "The Echo Nest Developer's API.
The most popular API, in terms of mashup count, is far and away the Google Maps API, which accounts for 41% of all mashups. But when it comes to the most popular pair of APIs, Flickr and YouTube mashups are the most common. Not to be outdone, Google Maps joins Flickr in a near second place.
There have been a lot of new socially based mashups showing up recently. In fact, we recently topped 700 social mashups. While many of these use the Facebook API or Twitter API, there are many more social APIs. The mashups below run the gamut, though, yes, also include Facebook.