Also on the quest for low-power components, I was researching CPU power usage. You could probably guess this, but Intel isn't paying any attention to low-power anymore (after the brief 6 months where people thought Transmeta might be a threat). So if you want a new desktop CPU through any Intel IHV, you are pushing 70W+ through the chip.
6 months ago, you could buy a Tualatin chip, mostly marketed for servers (P3 core on the .13 micron process, with 512KB of L2 cache) that would use 30W at 1.4GHz and rather nicely outperform a current midrange P4 (well for everything but memory throughput).
Intel's doing a great job with Mobile chips (Centrino is amazing all around), but I'm still trying to figure out what to do with a machine I leave on all day.