I wrote one of these for Vestek, but this might be useful, seeing how it is open source. Anyway, it is nice to have a utility which tells you in which location on your classpath a java Class is actually found.
This is the bomb. Archives as federated filesystems. (Zip, tar, jar, etc.) This will be needed by diorama for dealing with personal spaces. My concept of Spaces is to mount a jar file, then write to it, then unmount and share it, with whatever level of encryption. Your project's tips-n-tricks, help files, etc., would be in a public space. Your contacts would be in a private, encrypted space. Then those spaces get sync'd through your server/account, and shared as appropriate. This library, TrueZip, looks perfect for the implementation because it handles multithreaded access to the archive at runtime.