I'm really enamored by songs that make some sudden shift, when it's completely unexpected. It can be changing time signatures, key, style, etc. The obvious example of this is the arcade fire, but I'm looking for more examples, and more variation of this sort. Math rock does this kind of change, only it isn't as accessible to me. The lovely feathers and wolf parade also do this sometimes. For example:
The Lovely Feathers - Photo Corners, Frantic
The Arcade Fire - Rebellion (Lies), Crown of Love
Wolf Parade - I'll Believe in Anything
more stuff like that

any suggestions?