In my house we now have two iPads (one 3G, one just WiFi) as well as a 3rd generation iPod Touch. Like many other folks, we also have guests over who bring their iPhones along with them, and as luck would have it, they often need to plug in their wall chargers while visiting.
It was frustrating to find enough outlets for individual wall chargers and so I went looking for a multi-USB charger that had enough output power to charge multiple Apple devices, including iPads that draw much more power than an iPhone or iPod Touch.
I found one! and if you’re interested in getting what I think is the best A/C adapter for any Apple device that uses an iPhone type cable for charging, you might want to check out the Lenmar ACUSB4 AC Travel Adapter 
I have this device in my living room with two iPads and an iPod Touch — all happily charging. And I still have a fourth USB outlet thats open and available for when guests come over. Not sure it can handle a third iPad but we’ll find out when my nieces come over with theirs, i’m sure. Worst case scenario is I have to get one more of these.
Its worth noting that it ships with international plugs in addition to a plug for use in the USA. Very versatile!
One last thing. I also found Extra Long 6 Foot (6ft) iPhone / iPad / iPod USB Charge and Sync Cables