Web APIs and mashups are not only of interest to the developer community. There are also research activities that look at how to improve various aspects of API design as well as services' and mashups' implementation and deployment. If you are interested in a cutting-edge research that may influence the future of Web APIs, then you should look at series of workshops on Web APIs and Service Mashups.
Our API directory now includes 46 research APIs. The newest is the Globus Online Transfer API. The most popular, in terms of mashups, is the Mendeley API. We list 3 Mendeley mashups. Below you'll find some more stats from the directory, including the entire list of research APIs.
For music enthusiasts who thrive on insider knowledge and detailed music conversation, WhoSampled would be just their cup of tea. It's basically an online community for discovering and discussing sampled music, remixes and cover songs. WhoSampled has partnered with The Echo Nest to provide the WhoSampled API that allows developers to access and integrate its functionality with other applications.