Websites on File Formats:
DAT-Formats
Describes a number of the PalmPilot .dat files, including Memopad, Todolist, Addressbook, Datebook, and USERS.DAT.
DOC Format Man Page
Describes the structure of the PalmPilot .doc standard text file format.
HackMaster API
How to Write a Hack and describes the Hack file format.
Palm Desktop 3.0 DAT File Formats
Data file formats for the Palm Desktop 3.0 MFC streams files. Included are address.dat, todo.dat, datebook.dat and memopad.dat.
Palm OS Developer Documentation
Official file format specs for Palm Database (PDB), Palm Resource (PRC), and Palm Web Clipping Application (PQA) files, as well as full SDK, Conduit, and web clipping documentation.
PDB Format Man Page
Describes the structure of the PalmPilot .pdb (Pilot Database) file format.
PRC Format
An attempt to decipher and describe the PalmPilot .prc file format.