I'm really looking forward to the arrival of a multi-port 12V power supply I ordered last week. With it, I'll be able to power multiple mini-itx and embedded devices, saving quite a bit of power supply space.
The one question that's burning in my mind is whether using one converter from AC to DC will save power. I think it will, but I'll have to try it to find out. Here's a link to a description of the one I bought:
UPDATE August 16, 2007: I've had the multi-port 12V power supply up and running for about 3 weeks now without issue, so I'd venture to guess its ready to go in to the staging environment now. Cool, now I just have to get my hands on more ALIX boards! (though I'll probably use intel little valley motherboards as well.