So just how is your App doing? Got calls on your API? How many? StatHat API makes it possible to answer these types of questions statistically and to chart the data to pick out trends and patterns. Seeing is comprehending.
The legendary Billboard charts are now open for mixing, not by DJs, but by programmers. Billboard, a service of Nielsen Business Media, has a new API that lets developers search and read information from all the Billboard historical charts. The initial offering is its Chart service and later on Billboard will "roll out the Artist and Track services to add even more depth and perspective." the API is a simple REST interface that developers can send HTTP GET requests to in a familiar service/version/resource fashion. We've added a new Billboard API profile with details.
Chart APIs are useful and popular, and Google knows how to do them well, so they're continuously adding more features and options for customization to their Visualization API. The Google Code Blog recently highlighted a few of the newest features.