In reply to mypyrex:
> Thanks. I see there is an Anker 20100. Do you know what the difference is?
With Anker the numbers generally refer to the batteries in mAH, this pack would have over double the capacity of the Powermonkey that you linked to in your first post.
Mine is a 20000 mAH pack and I used it exclusively to charge my phone during an intensive day of travel and meetings yesterday. With a lot of phone calls and data used I had to fully charge the phone at least twice during a 20 hour day and the battery pack didn't even drop a single bar on it's charge meter.
You might gather that I'm rather impressed with Anker battery packs, hopefully someone will be along in a while to provide some balance and review another companies products