I was wondering about something like this project, but with a little twist;
If you have a power board/strip (or whatever you weird people call them, i'd call then a plugglehopper if it were up to me), with say 6 outlets, you could cut down the cost per outlet a fair bit, and it gives you quite a large area (inside one of those cases) for your board ect. But wait, theres more! Instead of it being wifi, build in a powerline ethernet module and a 4(?) port ethernet switch. That way, you could say... stick it in your lounge in your entertainment center, plug in your telly, htpc, games console, sound system, some lamps, your HD devices now have a solid, fast ethernet connection without running new cables, plus, you can control them all and monitor them all.
If I didn't have this house cabled, i could see myself buying 3 or 4 of them, one in the lounge, study, bedroom, maybe kitchen/laundry if those internet of things stoves/washing machines/driers catch on.