Well, now one of the manufacturers (D-Link) has a multi-purpose device, the AirPlus G DWL-G730AP Wireless Pocket Router/AP (DWL-G730AP). Here's what they say about it:
The DWL-G730AP supports multiple operation modes including: Access Point (AP) mode to create a wireless connection; Router mode to share an Internet connection; and Wireless Client mode to connect an existing wireless network. Easily switch between these modes by using the 3-way configuration switch located at the bottom.A SWITCH to set the mode!
But wait, there's more!
In AP mode, the DWL-G730AP adds support for 802.1x user authentication with an external RADIUS server.This makes it "enterprise friendly."
Here's a picture of it.
See the USB cable? It can be powered by the USB port.
I'll let you know if I get one.