Track Me Not

This is an interesting Firefox extension: "Track me Not".

It steganographies your really search queries by hiding them in a
stream of "random" search queries. Basically, it spams various search
engines continuously, so an attacker would have a more difficult time
discovering wht you are really interested in.

I kind of feel that a more random timing in the submit frequency would
help things, it can't be too difficult to discard all queries which
match a temporal pattern: say at a frequency of 120 seconds with a
standard deviation of a few points.

http://mrl.nyu.edu/~dhowe/trackmenot/faq.html