I am building someone a portable iPhone charger for Christmas. It's called a MintyBoost, and you can buy the kit on Adafruit here. (It's a really good electronics project for beginners).
Here's where I am so far:
I had to stop halfway through, because 1) I had to run into a meeting, and 2) I screwed up. I've had this problem my whole life - getting into a zone and jumping ahead of myself before reading all of the directions thoroughly, or skipping a step/overdoing it as a result. I soldered the diode (that black barrel toward the bottom-right) in upside down. Now I have to go out and buy desoldering braid to fix the thing.
Aside: Desoldering braid is hypnotizing. You put it over your screwup, put a soldering iron on it, and the braid sucks up the solder, essentially ungluing metal. So cool.
Hopefully the next time you hear from me on this, I'll have a working (AA battery powered, how cool is that?!) USB charger. To be continued…
EDIT: A request from Bud to see my soldering job --
(I'm usually a messy solderer; this is a new iron so it may just be a good one!)