I'll try to keep this chart up to date, but please let me know if I have missed anything, or got anything wrong.
Treo 600
Phone Technician 3.xx supports the Treo 600 fully. Phone Tech 4.xx works, but the 'Magic Ringers' feature is unsupported. Iinstall from the .prc links rather than the installer to avoid Magic Tones
Treo 180