I was thinking the low brow option would be an old laptop, but that's not going to suffice for someone who wants to keep up with wireless protocols (due to the same FUD under discussion). Obviously you can fix this (coreboot or modded BIOS), but specificity and tinker factor is going way up.
It's the rise of low power general boards that really make this practical. I tried out the ECS E2100 board for a remote server, and with a silver PS it drew around 15W from the wall. It didn't work with the RAM I already had though, so I ended up going with an i5 which still only measured around 20W before I put drives in.