First off, via Lifehacker, we have 12 killer apps for a Palm-based PDA:

Your Palm PDA can do a lot more than just contact and calendar management. Stock it with the right software and it can play music, stream RSS feeds, keep you entertained on the road, and even get you where you’re going.

There’s some good stuff on Lifehacker’s list. Some I already have on my Palm T|X (Pocket Tunes Deluxe) and some that I must immediately install (Numberz, Today).

And then we have palminfocenter.com with a list of must-have Treo freeware apps:

In this article PalmInfocenter highlights some essential must have Treo freeware applications. There is a wealth of free and open source Palm OS software out there. Read on as we take a look at 10 great programs, as well as a few others,

While the list has a few Treo-only programs, most work on other PalmOS devices (including the truly amazing TCPMP media player). Plus, all the apps on Palm Info Center’s list are free!
As soon as I can find time, I’m gonna sync up my T|X and fire up some of these proggies. This should be a lot of fun!