For some reason, I still can't get over the fact that The Art of Portal 2 book was cancelled. Well, here's the curated gallery for Portal 2.
Fan Art and Miscellaneous
You can find more Portal 2 fan art on Deviantart.com.
Here's the ending song of Portal 2 by Jonathan Coulton
Below: A Spoof by freddiew on the portal gun
Link: Portal 2 (Amazon.com)
Check out more galleries.