USB/AC cradle that charges phone when computer is off?

[marklyn]

OK, I bought one on ebay for $20 and asked before the sale if the cradle would charge my phone _without_ having to be connected to a computer. The answer was yes. I received the cradle (from Hong Kong) and it will only charge phone when connected to USB! The AC adapter must only charge the battery compartment.
I want a cradle that I can hook up to my computer by USB and be plugged into an AC outlet so when I need to sync, I can sync, and when the computer off the phone will still charge from the AC adapter.
If anyone knows about one that does this, please reply with a link or model of one.