[aleph_naught]

Not hard to do in Chrome, just point to a different user-data-dir for each category of browsing you need. I have three, one for general browsing, and two others for gmail accounts. That way I can use google without being logged in to the 'general' browser; and use the other two just for gmail. This way I never have to log out or clear the cache after checking email. I can be logged into two gmail accounts at once without my web history being directly tracked.

Example:

    /usr/bin/google-chrome --user-data-dir=/home/bleh/.config/gmail http://www.gmail.com

[beagle3]

This still makes you vulnerable to panopticlick style browser identification. Different browsers are a little better in that sense.