I'm guessing this could be done in the UK - we have a few major co-ops here; is the US the same?
One national brand I CAN think of that is a co-op is REI, I'm sure there are others though, lots of local-focused food businesses use a co-op model.
Costco and Sam's club (wholesalers / cash n carry) offer membership benefits but I think that's more related to getting air miles on your credit card.
I'm confused. What on earth does being a member of Costco have to do with credit card air miles?
The point I was trying to make is that whilst those companies offer a membership incentive structure its not a true co-op and you don't have an ownership stake in the company. You just receive some member benefits like cash back and discount coupons - similar to your credit card company giving you air miles.
The flip side is that cooperatives are run like businesses. The electrical cooperative will cut a shareholder's power as quick or quicker than a for profit utility when the shareholder fails to pay their bill - I've been to my client's office on "Cut Off Tuesday."
According to this site there were 724 purchasing co-ops in the US in 2009. Those would be stores like REI or food co-ops where the consumer is part-owner.
The total number of cooperatives, including worker-owned business like Land o Lakes and ACE Hardware, credit unions, and utility co-op (25% of US power generation is publicly owned) is 29,000 with revenues around $625 billion.
I know the idea is a bit muddled. Something along the lines of working on Linux reduced opportunity costs compared to alternatives.