Palm sync to OS X
While there are utilities available on VersionTracker that will allow you to sync iPaqs with OS X, all Palm PDAs are officially supported by iSync on OS X. I use a discontinued model Palm m105 connected to my PowerMac through a Serial-to-USB adaptor and the two work well together.
If you are looking to buy a new PDA now seems to be the ideal time. The latest Palm offerings have great features like high-res colour screens, Palm OS 5, built-in cameras, card slots, BlueTooth, etc and the prices compare very well with anything the competition is offering.