I would love to upgrade to something like that; maybe someday. My phone is one of the early Android phones. I does most of what I want it to, but just barely. Anyway, here are the apps I've found most useful:
Battery Monitory Widget (from 3C)
System Tuner (also from 3C)
RealCalc Scientific Calculator (I just prefer RPN)
SMS Backup and Restore
I soon plan to get a OBD2 bluetooth adapter and the Torque Pro app as well. You might be interested in that if you ever do any work on your car.
There are others I use a lot as well, but those are more specific to me and my life and probably not of interest to you unless you have the same bank, carrier, religion, etc.