From Just Solve the File Format Problem
MonkeyCard is a Palm OS program for sending postcard-like messages, developed by a company named Primate Systems. It apparently has a graphics format associated with it.
- MonkeyCard demo software, from archive.org and Tucows
- XnView claims to support MonkeyCard images, but it's not clear what form it wants them to be in.
- samples01.PDB from the demo software (unverified)