Found out a cool site that checks the ID of a user/browser.
This is what they do:
“We investigate the degree to which modern web browsers
are subject to device fingerprinting” via the version and confgura-
tion information that they will transmit to websites upon request. We
implemented one possible fingerprinting algorithm, and collected these
fingerprints from a large sample of browsers that visited our test side,
Related to the subject is a book “How to be Anonymous Online – A Quick Step-By-Step Manual” writen by Anna Eydie http://www.annameydie.com/
Anna has a modified Linux that she calls “Tails” witch I downloaded and will be testing.