Vashon Software

It is only somewhat known that ad servers and aggregators track your visits through many different web pages with third-party cookies. But just getting rid of your cookies periodically is not enough to guarantee your surfing habits aren't known: Adobe's Flash player (also active on many web pages) can also be used to track one person's browsing behavior across many sites.

Generally this is just obnoxious, as it just results in targeted ads being sent your way. However this can be used in a darker fashion by less scrupulous individuals. It also should be possible to use these local storage files to reconnect you with all your old surfing habits - even if you try to be careful of your cookie use. (I only delete mine every 12 months or so.)

Surprisingly, the solution lies not on your computer, but on Adobe's web site (they now own Macromedia), at:
www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager07.html
where you can disable this setting on a machine by machine basis. (I suspect this implies they still capture all the data about you still, just that they don't release it.) Their explanation for all this is at:
www.macromedia.com/support/documentation/en/flashplayer/help/settings_manager.html

Moral of the story: Not all cookies taste good, eat (and surf) with discretion!