Following on from How To Find Unused Jars?…
There is the strangely-named JBalboa.
It is a separate static-analysis tool that can discover which jars in a given directory are never used and find which Jar(s) a class can be found in.
There is a GUI:

And there’s a command-line mode, as well.
There’s also JBoss’ Tattletale: “Betraying your project’s naughty little secrets.”
Runs on the command line or via an ant task.
Useful stuff!
