Topic: 8+ hr battery pack for $31.42, no mods needed.
inspired by a make magazine blog article I saw, I decided to try this:
It is currently listed on Amazon.com for $31.42
It ran for about 8+ hours with full brightness on and widgets cycling every 10-15 seconds, although it was not playing any sound at the time. It showed a cpu load average of about 2.5 (as reported by uptime).
I'll retry it next week with sound on (I didn't think about that)
I didnt do any sort of mods ... just plugged it right into the back.
I plan to use my Chumby to drive a little robot around the room as a demonstration for a programming course I am teaching ... and this powerpack will probably work just fine. It is conveniently shaped, and so I am hoping I'll be able to cobble together the robot, battery pack and chumby with velcro and/or duct tape :-)