feather is a small, process-based framework, intended for writing applications that are defined by plugin-based functionality.
Applications are defined as a set of messages that will be generated and responded to by some plugin being run by an application. For instance, a music player might be defined by the commands "play, pause, skipsong, skipalbum". As long as a combination of plugins results in at least one generator of, and one listener to, each message required, the application will happily run (perhaps not with the behaviour you expect though.).
This is currently very much in beta. There are probably massive ugly problems. Patches welcome.
For an example of an application using this, checkout out Pyrana (https://github.com/jdodds/pyrana).