It seems like there are just never enough electrons in your phone, right? With just a few thousand milliampere-hour, it can be easy to drain your device before there's an outlet handy, so it's a good thing portable battery packs exist. If you're carrying something extra anyway, you might as well go big. A Crave Travel Pro 13,000mAh battery that should work nicely is on sale over at Amazon.
I don't need to tell you this is a good deal – we've seen it pop up before and it sold out pretty fast. Today you can get the Nexus 7 in either 16GB or 32GB sizes for $170 and $130 respectively, but it's US-only.