Anime mix up/parody videos

I've found quite a few funny or awesome mix up or parody videos which combine the musical themes or art style of 2 animes and mix them together, for example this one which i just found and i think is awesome, which is the Nichijou opening with characters from the Madoka universe
http://youtu.be/hZxUinHVUbU
(I love how it even has the characters from the manga :3)

or the Durarara! opening with characters from Steins;Gate:
http://youtu.be/NIBEQIcU0Lg

There's even ones that mixes anime with things that aren't, such as the Durarara! ending theme with Harry Potter characters, or the the Higurashi Kai opening theme with Final Fantasy 7 characters.

Anyone else got any to share? i love these things :D

http://www.youtube.com/watch?v=zi2NXUQ16wc
Nitro+ parodies Madoka's opening with their music mascot, Sonico. Enjoy the other nice Nitro+ cameos if you can spot and identify them when they all show up. Nitro+ took down their video, so this Spanish subbed version is all that's left. Enjoy.

http://www.youtube.com/watch?v=RwVJ1_Un6qU
This SZS-Ace Attorney parody is popular and pretty well enjoyed.