For those who aren't aware of what i'm talking about

Wikipedia article
There are some bloody amazing MAD AMVs out there, share them here:

Black Lagoon x Haruhi - The Melancholy of Balalaika

Angel Beats x Black Lagoon - Angel Beats! 偽OP_BLACK LAGOON HD

The World God Only Knows x Code Geass - 神のみぞ知るセカイOP絵コンテっぽい動画【完成】

That last one isn't particularly visually impressive, just a personal favourite