What would make sense to me more than an SSL co-op would actually be a registrar that gives you a free wildcard certificate for every domain you register. You almost always need a certificate for every domain you use, so why not bundle the two? I wonder if doing a crowdsourced bootstrap of such a registrar would work.
I'm not averse to that idea, in principle. Heck, that sounds like a nice complementary business idea -- you run a DNS registrar that offers a free domain-validated wildcard certificate with every domain sold, and get your certs from the co-op. The costs would be minimal -- there's bugger-all required to start a domain name reselling business, and SSL co-op membership is shaping up to be more on the "consumer" end, rather than "retailer" cost structure, so there wouldn't be significant costs there, either. I don't think it would need crowdsourced funding to get started, honestly.
The game-changing of the SSL co-op has already started! New business models are taking shape! (grin)