Another one spamming -.-

Here are some of my favourite boredom-quenching links.. I usually bust them out while playing PW in fact. Click the combo, alt+tab, click the combo, alt_tab.. wash, rinse, repeat... auto-fly somewhere.. alt_tab.

Try these on for size:
http://www.freewebarcade.com/physics-games.php
http://******-am-bored.com/
http://www.cracked.com/ (This one is particularly good)

And some of the best webcomics out there:
http://www.somethingpositive.net/20012002archive.shtml (A bit of an acquired taste, some fairly serious storylines and character development, but well worth the time if you get into it, and a barrel of laughs all the way)

http://www.giantitp.com/comics/oots0001.html (Funny stick figure adventurers. Based on D&D. What more can I say?)

http://www.pvponline.com/ (A gaming comic earlier on, but gravitated towards more less game-related storylines lately)

http://explosm.net/comics/ (Cyanide and Happiness.. I'm sure you've heard of it. Sheer indescribable awesomeness)

http://www.smbc-comics.com/ (Single panel comics at their best. It brings the funny)

http://www.sinfest.net/ (Almost painfully liberal and left-wing, but clever and well-drawn)

http://www.xkcd.com/ (XKCD... you've probably heard of this one as well. Kinda geekier. I don't get a whole lot of them. Programming jokes and whatnot. But the ones I actually do get are damn good)

http://www.starslip.com/ (Surprisingly good comic.. it helps if you imagine that the main character has the voice of Zap Brannigan from Futurama. Seriously)

Go forth and amuse yourself!