@realjohnboy,
Not a bad idea. The top firms in terms of revenue & client numbers in Cicerone's list United Health Group, Wellpoint, Aetna, Humana, and Cigna, in order. Together they represent 84+% of the total revenues of the 13 firms on Cicerone's link. I'm not sure of the for profit/not for profit mix in this group, but it should be easy to find out.
It is interesting to note that Cicerone's link also provides the % change in profits from the previous year (2005) - the firms averaged about 20% increases in profits from the previous year but much larger increases in revenue, which indicates that their profgits were declining in 2006 - even at these low levels.
Everyone complains about the constraints & chickenshit applied by insurers to healthcare costs. However that is how they limit fraud and abuse. The government is generally far less effective at that sort of thing - whitness the 200 million Medicare scam just uncovered a couple of days ago. When we end up on a bureaucratically "managed", bankrupt healthcare system with pipsqueak clerks who that tell us how much of a shrinking pot we are entitled to, we will have lots of time to regret this "change".