Couple of cool things I've done with the Treo the last week and a bit. The main thing is switching launchers from Launcher-X, to Initiate. This is a really sweet launcher that allows you to just type what your looking for and voila. Including contacts, apps, files, etc. Check out the website for the full deets.
He also has a number of other software that I use and love. The genious! program makes searching for things very easy as it can search online or locally etc.
The other one I love is Power hero. My favorite parts of PH are simple, the scheduling of the phone on and off, and the bluetooth auto connecting when in my car. Yes the treo takes a few seconds to connect but I just answer by picking up the phone and in no time at all the speaker in my car kicks in.