Palmphi - A new tool to simplify the creation of applications for palm devices. - http://www.digital-kingdoms.net/palmphi/
OnBoardC Suite - A C-language development environment that runs on and builds code for, the Palm handheld platform. This is a Sourceforge project. - http://onboardc.sourceforge.net/
PocketC by Orbworks - A small C compiler that runs on a PalmPilot. Develop and compile code on the road. Shareware. Can not compile after 45 days unless registered. The PocketC runtime is available for free. - http://www.orbworks.com/pcpalm/index.html
PocketC for PalmOS Resources - Source code, documentation, libraries, and sample applications (applets) for PocketC. Provided by Orbworks. - http://www.orbworks.com/palmres.html