John Wiegley's Pilot perl module: Allows installing data and managing databases in perl scripts.
Palm OS Application Development HOWTO: Provides information needed to develop applications for Palm OS devices, using Linux as a development platform.
Palm Pilot Software Development with Linux: Alan Kennington's notes on programming for the Palm.
PiTcl: Extends Tcl with commands for the communication with a Palm.
prc-tools: Cross-platform tools (gcc, binutils, gdb patches) for the Motorola 68328 Dragonball CPU.
Pyrite: Extension package for the Python programming language which allows access to Palm Computing platform devices and their data.