1. Atari Breakout
Type "Atari Breakout" in Google Images and you'll be able to play the game.
2. The Answer To Life
Homage to The Hitchhiker's Guide To The Galaxy
3. Festivus Pole
If you're a fan of Seinfeld, you'll recognize that pole to the side of your results when you search "Festivus"
Your results will be tilted
5. Play Pacman
Go here to play pac-man!
The answer is obvious but the question is fun!
7. Zerg Rush
Play a fun tough game when you search "zerg rush"
8. Blink HTML
Make the word "blink" blink.
9. Vintage Google
Search "Google in 1998" to use the original design.
10. Nag A Ram
For those word nerds out there: Search "anagram" and the Did you mean: is a fun little play on the search.
11. The Loneliest Number
Look up "The Loneliest Number" and the number one will appear everywhere.