CheckBook is a nicely written piece of software for managing expenses. It's got goodies like multiple accounts, running totals, and transfers from one account to another.
Plucker is a great tool for downloading websites for offline viewing. It's open source, with the conversion program available for every major OS. Plucker is also showing itself to be very useful for eBooks. The Plucker Book Repository has many books available for browsing and .pdb download.
I'll include another update for games at some point. To whet your appetite, here's Patience. It's free, and it's got 15 solitaire variations in one tiny app.
Check out PalmOpenSource.com for more apps.