J-Pilot is a full-featured desktop organizer application for the Palm Pilot that runs under Linux and UNIX. It includes support for Datebook, Contacts, Address, Memo, Memos, Todos, Expenses, and has plugin support. It uses the GTK+ libraries.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.