DeathKnight.info. They have a fun little community on their forums, and their front page highlights most of the really cool stuff that happens to come out of it. The bulk of it is, of course, Death Knight news, but it also shows off a lot of the really random things WoW players do.
Magtheridon, once one of the hardest raid encounters in the game (depending on who you talk to), has been 4-manned by an Unholy Death Knight (who you may have read about previously), a Retribution Paladin, a Restoration Druid and a Holy Priest. If you've done the fight before, you might be thinking to yourself, "That's not possible. You need more people than that just to click the cubes!" Apparently that is not the case. They didn't bother with the cubes, they just healed through the damage.