This tip isn't to save your time but to waste it. These are some flash games/animations I found on the web through Stumbleupon!

Tilt - Balance a stand on your finger. Simple and addictive

Icon war - Icons fighting each other

Interactive art - Get immersed in the picture

The Angry nintendo nerd (youtube) - Finds fault with crappy games and rants about them. hilarious. Parental Advisory.