Post yours. No need to be automotive related. Some of mine:
DslReports.com - Lots of active forums, ranging from hardware & software help to crazy general & political threads
http://www.dslreports.com/forums/all
Ain't it Cool News - Entertainment & Movie site
http://zone.aintitcool.com/index.php
FatWallet-Users post great deals online and in Brick & Morter stores