I know I am lucky to have this setup, but I keep 2 laptops and 2 tower computers or 4 separate computers. 1 for biz, 1 for downloading and email, 1pc for gaming, and 1 for activities best kept in private browsing..
(Maybe something as simple as physical location, color, a "sticker", or something else altogether.)
That's exactly why I find this setup so appealing; it really works with the natural tendencies of our minds, as opposed to constantly presenting us with a situation where we have to choose not to do one of the many distracting options just a twitch of the finger away.