I was recently invited to join DVOR.com which is affiliated with opticsplanet.com which I have received excellent customer service from.
Like ProMotive.com it a group membership site which offers discounts on select vendor products. The variety is smaller than ProMotive but it is mainly firearms related. Some of the items I noticed were well priced - for example Blackhawk holsters, Trijicon NightSights, etc.
Update 2012: DVOR has become more an "event sale" rather than a permanent store front. They run daily specials that are sometime very good. What is available in the store front changes dramatically so if you don't log in regularly you might be surprised. I get their daily sale "event" email and log in based on my interest in what specials they are running.
Here is an invite link (it is free) if you want to check it out: DVOR.com invite
*02/22/2012*
I just got a 5.11 Rush Delivery (tactical messenger bag) to fit a 17″ laptop. It retails for $99 and bought it through DVOR for $65. Bag review forthcoming…Great price and customer service!