I’m constantly charging my devices. I often have two USB cables. One plugs into my computer. The other is attached to an adapter which I then plug into an electrical outlet.
Soon you’ll be able to plug your USB cable directly into a wall outlet. You just swap a TruePower UCS power outlet for your regular outlet; no fiddling with the wiring like other solutions. You still have your AC outlets, plus got two USB power ports rated at a sufficient 5.0V 600mA.
The outlet costs only $9.95. But it’s not available yet. Per the website, it’s “scheduled to begin shipping in early 2010” but “is currently waiting on final UL Approval.” Probably best to wait to make sure that plugging your USB cable into a wall outlet isn’t, well, a shocking experience.