I've been playing around with my Pi and I can't get my BenQ monitor to play ball with it, so I used my TV downstairs to get it setup, but I was too lazy to fiddle around with plugs, so I whacked in my TeckNet 7000mAh battery and the Pi runs fine off it. In theory, could power the Pi for 6-7 hours I reckon, if not more.
Ideal for laziness etc. >.>
http://www.amazon.co.uk/TeckNet%C2%AE-D ... 943&sr=8-5