Paranoid Browsing is currently available only for Google Chrome, and it functions by opening an additional web browser tab or window in the background that randomly goes trough a customizable set of generic websites while the user does his usual web surfing.
PB will also click on links on these pages, going deeper into the site and mimicking the pauses that a user would take to peruse the pages on which he landed.
"PB currently browses the 'standard American' set of web pages, but you can easily modify this to look at ponies, go carts or whatever else you want profilers to think you're interested in," says West.
He offered the code for the plugin on GitHub for free, and has asked for other developers who use it to improve on it and freely ask to merge their changes back into the main project, as well as to analyze the code for security and robustness.
The project was also featured on BoingBoing by Doctorow himself, and has generated quite a good discussion.