I don't know of any that are battery powered. I'd imagine most are 12V (my netgear is 12V) or 6V so you could get a rechargeable gell cell and a barrel plug that fits the bridge and run it off of that. What's another object sitting there at this point?!?
Or, how does the Asante Micro get it's power? Maybe you can tap that, or something off the laptop.