The Iconia A500 takes a 12V / 1.5A supply, and I managed to find a "universal" one at DSE. Of course, none of the plugs actually fit my tablet.
PBtech, JB Hi-Fi, and Surplustronics have not been able to help me.
Does anybody know where to get a new power supply for the A500? I'm guessing I'm just going to have to buy an official one through Acer. Very frustrating that it uses a non-standard (or at least not common) power rating and a non-standard plug. It's like owning an Apple product!!