The 650 is all you need. Plus for entertainment, you can use AIM, listen to MP3s and use them as ring tones, watch movies, and use emulators (the GB/GBC, NES, TG-16, and SMS/Game Gear emulators are all AWESOME).
My Treo 650 is used for web browsing, scheduling, and also doubles as my MP3 player when I'm in the car. It's just too damn good.
I'm going to be giving this phone up (I'm sure my dad will take it) when I leave for Japan next month. Definitely going to miss it and I hope there's something similar I can get over there.
Sorry, but he pays the bill for the monthly service, so it goes back to him. Getting this phone for free and not having to pay for the service is what he's done for me.