Here's another one I've used, the Fender Amp In A Can , smaller unit, battery doesn't last quite as long between charges, about 2 hrs, but it is small and easy to pack around, and has pretty good sound, although not all that loud. Works well for small outdoor parties where it don't gotta be that loud. I've carried it to parties on a motorcycle and with my ol lady on there too....

The battery powered deal is pretty cool though....
Willy