When I go on an overnight and need to recharge, I have these USB needs: cellphone, GPS, two cameras, a bulk storage battery, front Expilion headlight, front ORP blinky/horn. On a non-USB plug I have my DesignShine taillight. On the AA & AAA front, I have a Cateye 1100 taillight, a Cateye red/white helmet blinky, and a 4xAAA head lamp.
So I've purchased a 10-Port USB charger.
If nothing else, it'll prevent me from walking into coffeeshops with two powerstrips which is not a very cool-kid aesthetic, and it'll reduce the space requirements.