Wireless Noise
Carnegie Mellon’s wireless network makes me sad: I get about 20 KB/s of constant noise (all day, every day) from, mostly, Windows computers announcing their presence to the outside world via broadcast packets.
In the “network” window, this looks like that:
If this is a secret ploy with the intention to empty everybody’s laptop batteries as fast as possible, it’s working! 
Then again, unlike University of Karlsruhe, CMU puts power outlets into every seat when they drop a bucket of money to renovate a lecture hall. At my home university–with the exception of the new library–laptops have to be mostly powered with their owners’ love and respect: Places with appropriate power connections are rare.
