I don't have any opinion about the health insurance co-op legislation that some people are talking about, but given the role of co-ops in left-libertarian economic models, it's probably worth looking into. Here are two views:

• A DKos, slinkerwink seems offended that Blue Cross Blue Shield Wants To Become A "Co-Op!". His main objection seems to be that non-profits still give their top execs immense salaries (same is true for hospitals and universities).
• At the Daily Dish (and Reason), Peter Sunderman ponders Those Mysterious Co-ops, and gives some history of health co-ops in the USA.