I've recently found an HP Jornada 720 gathering dust in my last moving box, and have been collecting a few links for later tinkering:
- Miscellaneous downloads including an IrDA driver and a Remote Desktop client.
- One likely option to get Linux running on it (if I ever bother, since there seems to be no power management), taken from this post.
- The Jornada Archives - for the "Familiar" Linux distro.
- Andreas WinCE Personal Java (and how to get it to work)
- Emacs for it, if you absolutely must.