Neiko 3/8-Inch, 55-Degree Close Quarters Right-Angle Drill:
http://www.amazon.com/gp/product/B000XUHA8C/ref=oh_aui_detailpage_o02_s01?ie=UTF8&psc=1
Cons:
- paddle switch can get in the way on deeper bowls (a longer sanding extension would probably mostly solve that)
Pros:
- variable speed is nice, and easy to control on the fly
- seems moderately well built for the price
- not overly heavy
- heckofalotbetter than hand sanding
I also have used my 5" ROS on the outside of larger bowls but its kind of unweildy on anything but the very largest. The little metabo Vaughn linked to would be handier.
Also don't skimp on the sanding pad/attachement setup, I bought a cheapo PSI set for the Neiko and wish I'd sprung for a bit better set up front - money down the drain.