jwz recently got himself a Treo 650 as well, and ask for software suggestions. I suggested PSSH and AvantGo, and looked at the other suggestions. There are a few I may try, but I did install Graffiti Anywhere. I'm very used to the keyboard, but sometimes you just need to jot a quick note, and with some applications selecting the right field and then typing text into a box, etc, is just a pain. Since the Graffiti 2 libraries are still in the Treo's OS, but it lacks an input area, this software has the effect of enabling Graffiti on the Treo.
I also installed KeyCaps650. This allows you to type capital letters by holding the key down longer and punctuation with a double-click. Sweet!
Finally I installed Directory Assistant. This is basically an application that front-ends YP.com. It provides a slick interface for looking up numbers and addresses, and it will also kick open the browser for mapping the listing you want.
kyrene - anything you recommend from your Treo usage? (That is, if you see this when you get back from vacation...)