TV Tropes.

Ye gods and little fishes, I started out at their QI page and now I'm going through The Colbert Report's Crowning Moments of Awesome (by way of the Top Gear page and Buffy Crowning Moments of Awesome and Sherlock and Sociopathic Heroes and) and watching a lot of clips and I've still got a bazillion tabs open (and that's aside from the AO3 tabs, like I don't know where to go if I want to find Mystrade or Sherstrade fics again :P)...

My brain hurts.

Also, this is apparently called a "Wiki Walk." Previously I'd just called it "getting TVTropes'd."