What is it?
Github Watcher is a GTK+ desktop application that monitors your Github watch list and keeps a synced copy of each watched repository on your local machine.
Is it ready?
Yes! It works for me on my Debian box, but YMMV.
Can I see it?
Screenshot is at http://github.com/jmhobbs/github-watcher/blob/gh-pages/images/screenshot.8c0d64d.png and may be a bit stale.
There may be others I'm not remembering, but here are some definites.