Mostly, full group or raid wipes are lame. Really, really lame. But sometimes, every once in a while, you'll have a wipe come along that is so spectacular, so fun, and so memorable, that it almost makes the repair costs worth it.
So let's hear your best wipe story. The shot above wasn't actually a wipe (we finished the Tiger boss in ZG with one solitary hunter left, and it was awesome), but my guild will always joke about the time our Warlock lead accidentally fell off the bridge in MC and onto the head of Golemagg-- who then proceeded to make his way all the way around the instance, grabbing every lava pack and puppy on the way, and crushing every single one of us out of existence. TS was just full of people screaming, yelling, and laughing the whole time. Oh, the Horde-anity!