Cachemate
http://www.smittyware.com/palm/cachemate/
I use Palm for it everyday and it works flawless.
Actually had a CE device but at that time no cachemate support for it.
Do not be fooled, the palm OS is just find for waypoints and data sets. :)
It is very simple to load your filter in GSAK then export to PDA .. Hotsync and I have 2000 caches for Arizona just waiting to be hunted down.
My recommendation if you have to get a new one would be to not get a Palm OS. The operating system makes it harder (or at least more cumbersome) to get geocaching software to load waypoints, from what I've found anyway.