How Much energy does the Internet use?

Chris posed a very interesting rhetorical question today.

How much energy does the Internet consume?

Broadly, this means electric, mental, organizational, etc.

Specifically, considering all the networked devices and the electrons going through billions of connections, how many Watts do we dissapte in the ether?

Can you count computers, translate to electricity demands, and then translate to things like barrels of oil or global warming effects?

Then can we ask:

Of the energy used by the Internet, how much is wasted by Spam?

And then to get very Lefty/Green:

How much does Spam contribute to the destruction of rain forests?

How many Iraqis die to support the energy demands of Viagra ads?

whimper.