This is a fun silly game. You input 0s and 1s as random as possible.
Some algorithm tries to guess what you are going to input based on your patterns.
http://seed.ucsd.edu/~mindreader/
It is extremely hard to win without a thought strategy, almost impossible.
And if you want to test a sequence versus two or three word distribution this is a cool tool:
http://www.khanacademy.org/labs/explorations/frequency-stability