These illusions are amazing. Many involve the effect of motion on perception –click through to check them out, and make sure you play with the settings as applicable.
Let me know what you think in the comments.
Update: check out the finalists from previous years too – links are on the left.
The top illusion for 2010 is amazing.
I can’t resist adding this update on the gorilla illusion (see the 2010 finalists page if it won’t load):