Umm. Wow. I just bought an energy consumption meter for £6 on eBay, but even "rip-off Maplin" sell them for around £10~£15.
Granted, it's not wifi, but it does everything you need it to do. Volts, Amps, Watts, PF, VA, Cost, kWh.
So, power consumption of some household appliances:
Panasonic 46" 1080p plasma TV. Standby: 0W (min 1W measure). Operational with no signal 130W. Average TV around 350W, peak 635W with random black/white noise pattern. (Power limiter kicks in after 20 seconds and drops power consumption to 550W max.)
Samsung 40" 1080p LCD TV. Standby: 0W. Operational: 180W.
Yamaha RX-V450 amplifier. Standby: 0W. Operational (no audio): 40W. Operational with average TV program audio 44W.
Desktop PC. Standby: 8W. Operational: 180W idle, 200W under load.
Cheap LCD monitor (24"). Standby: 0W. Operational: 40W.
Laptop (Thinkpad X201): Standby with charged battery: 0W. Operational with no battery: 13W.
PlayStation 3, 80GB early gen "fat". Standby: 0W. Operational: 145W**.
** This is probably where they get their "170W" figure from; while on the home screen (not playing a game) it does use a metric ton of power. However, it also makes quite a lot of noise. I doubt I'd leave this running.
As can be seen, almost everything, bar my desktop, uses less than one watt in standby. People fuss over standby power, but it really isn't a big deal. Watching my plasma TV for 2.4 seconds uses the same amount of power as it would in one hour being in standby (the service documentation rates it at 0.2W.)