I've been meaning to post about this for some time. The company I work for encourages us to leave our PCs on overnight (for anti-virus updates I was told). I at least switch my monitor off (and I reboot my machine as I know they need a good clear out regularly for optimum performance, in my experience at least), many don't. According to this article on the BBC, a standard CRT monitor, when switched on during the day and left on standby overnight, eats through £150 of electricity in 5 years. With 200 computers that adds up to £30,000, and that's just for monitors, I don't know what an average base unit sucks up in a 24 hour period. The article points out that in many companies it would be cost effective to employ someone to go around switching all the machines off.
According to our website we employ 21,000 people worldwide, assuming they all have one monitor, that's £3,150,000 over five years or £630,000 a year (admittedly we have to have them on during the day). I'm thinking of sending an email to the IT boys to find out why our machines need to stay on.
On the home front, the article also points out that TVs draw power when in standby, up to 13 watts for older models. Save yourself some money, don't leave things on standby, switch them right off.