Here's my list:

www.jensonusa.com
www.performancebike.com
www.nashbar.com
www.aebike.com
www.harriscyclery.com
www.speedgoat.com
www.pricepoint.com
www.probikekit.com

I use Jenson alot because they're local to me and have a pretty good range of stuff.

Speedgoat can get alot of the QBP stuff that other retailers may not stock or be willing to order.

Harris has alot of the little rare bits and pieces that you can't find easily elsewhere.

Nashbar/Performance is good for the price if they happen to have what you want/need.

PBK sometimes has killer deals on tires and components.