If you use Firefox, try using the Self-Destructing Cookiesextension (depending how you have it set up, it will automatically zap cookies when you leave a site...and you can whitelist sites where you don't want the cookies zapped...like Free Republic)
If you use Chrome / Chromium, try using the Vanilla Cookie Manager add-on. One button zapping of cookies (and you can whitelist sites where you want cookies retained).
I still believe the browsers themselves are collecting/reporting to their mother ships.