Codez4Palm is an extensive database of PalmOS registration codes packaged in a convenient app you can bring with you right on your Palm OS device! Also features MultiUserHack integration to allow registering individual apps with unique HotSync IDs. You can also keep track of your own registration codes by adding them to a private database within the app.
For older devices incompatible with the app, a text version of the database can also be viewed below.
(*Based on user feedback)