I’ve not had great success finding non-Apple USB ports that supply enough power to charge my iPhone and iPad. Until recently.
The PowerCurve Mobile Surge Protector works really well. As far as I can tell, it charges my iPhone and iPad just as fast as the wall charger that Apple ships with new iOS devices.
The PowerCurve is very compact. It’ll fit in any travel bag. I even keep one plugged in behind my night stand so that I can easily charge my iPhone and iPad in the same spot.
At $20, it's cheaper (and more practical) than loading up on Apple wall chargers.
The number of iOS devices in my extended family has grown geometrically in the last year. There's no such thing as too many USB ports.
Update (3/20/2012): I've found that the PowerCurve does not fully charge the new iPad (3rd generation), so I would not recommend it for the new iPad.