Emulators

Copilot - Windows PalmPilot Emulator
Greg Hewgill created Copilot. In early 1998, Palm Computing took over development and maintenance of the emulator. It is now called the Palm OS Emulator.
http://www.hewgill.com/pilot/copilot/index.html

Copilot - Windows PalmPilot Emulator (Old)
The original information page before Palm Computing took over development of the emulator. Includes links to Copilot ports to many different operating systems and platforms.
http://www.hewgill.com/pilot/copilot/index-old.html

Palm OS Emulator
Emulates the hardware of the various models of Palm OS platform devices.
http://www.palmos.com/dev/tools/emulator/

Palm OS Emulator Skins
Customize the look of your Palm OS Emulator with a new skin. From Skinz.org.
http://www.skinz.org/