I'm currently experimenting using an external power supply (for cellphones) as a type of "UPS" for my Pi. It seems to work quite well. Can anyone think of a reason why this isn't a good idea? I got this: http://www.amazon.com/PowerBot%C2%AE-Universal-External-MicroUSB-Stainless/dp/B00CV11X84/
I then connected the power cable from the Pi into the battery, and finally the 5v power supply into the battery to keep it charged. So far, it's been working great. I can pull the power supply from the wall, and the Pi stays running. My goal is to simply have something in place to handle small/short power hits.