A v. 2.0 Minty Boost I just bought from AdaFruit (very similar to the one in Lady Ada's Instructable except that it apparently works better with iPhones now). I used a larger Altoids-type tin, not the gum tin - that gives me room for a spare set of batteries. I also made the hole in the side without just clipping a notch. Nothing special really, but I hadn't really seen that so I figured I post it.
Step 1: Making It
The Minty Boost is made per the kit instructions (available at Lady Ada's site). I wanted the USB port to be fairly flush, and I didn't want a big notch in the side. I had thought about using a Dremel to cut the hole, but after googling around a bit saw a mention of just using a hole punch. I put the minty-boost inside where I wanted it, then marked the outside with a pencil at the approximate location. It worked great - made 3 overlapping punches. Then I used a small file to enlarge the hole to the right size.
Step 2: Why Bother?
I keep the Minty Boost in my bag as an emergency charger, Although the circuit is supposed to draw very little power at rest, eventually it will drain the batteries. This way I always have at least one fresh set. I've got some low drain NiMH on order so I don't have to keep buying AA's. I've tried it on an iPhone, iPod Touch, and old iPod mini - worked fine for all of them.