A couple of weeks ago, I built a Fakebook page from scratch. Now that I'm done, there is a huge collection of templates available at keynotopia.
Keynotopia has put together design elements from Facebook, iPhone/Pad, OS X, that google phone/tablet thingie (what's it's name again?) and Blackberry. They can be assembled and animated in Keynote, then exported to Quicktime for further use in an NLE.
The whole pack costs 97 bucks.
Just a sample what you can do with it:
Couldn't they come up with that thing when I could have needed it?