I’m involved in building a web application which aims to promote Open Source “projects and adoption”.
In realizing that I’m interested in collect some statistics on open source projects used in order to provide some “common sense” on these projects (size, stability, adoption, hype, community health, and so on). Despite de difficulty to define a valuable set of indicators (and useful metrics on them…) I think a nice starting point could be represented by Ohloh.
Basically on Ohloh every registered project can be assigned to some people who care about feeding in data on such projects (ok, that’s really basically).
Despite the fact that personally I don’t like to depend to a unique source of information, the data presented by Ohloh are gathered from the “community” behind each project (line of code, code/comment ratio, number of contributors, number of commit, activities in last months, etc.).
Last but not least, Ohloh provide a simple but effective set of RESTful API, well metered.
The first thing to do is to register and obtaning a key, even if you simply want only read data. After that you can access all the information simply issuing an HTTP GET request with before mentioned key appended.
then you obtain a self-explanatory XML document.
I feel myself comfortably with such kind of API: simple and effective. For more info see the official Ohloh API page