Okay, I found this a bit interesting, don't know if you will. It doesn't really matter a lot, but still.
The Ps3 uses 380 watts an hour (source: http://blogs.zdnet.com/Ou/?p=356 , or just google it)
Compared to this, the Ps2 used 45 watts an hour.
The X360 uses 160 watts an hour
The original used ~ 70.
The Wii uses ~ 17 watts an hour when on, 1-2 when standby.
A comparison is that the Gamecube used roughly 30-40 watts (differing reports) when used.
The DS was hard to find anything about, same for GBA. One thing though.
I'm playing FE8 on DS now. It's a GBA game. Well, I play on minimal electricity, and it has played almost 40 hours without a refill now (the light just recently became red). So I believe that the DS uses about 3 times as much electricity as the GBA did.
PsP, no info.
BTW, this was just a little fun fact that I posted. It doesn't really mean anything
Prices if you live in USA (average price) should be around this.
24/7 use of Wii connect 24 365 days a year = ~ 1 dollar
Use of Wii for an average of 3 hours on a day (not necessarily played, but on), for the entire year = 2 dollars
3 hours Ps3 (on) a day average for the year = 40 dollars
3 hours X360 (on) a day average for the year = 18 dollars
In some parts of Europe, the prices are probably slightly higher.
