Very cool. I wish I had this when shopping for insurance a year ago. A "total annual cost" column would be helpful for making sense of the deductible/premium/co-pay relationship. Think of it as the "Price+Shipping+Tax" on shopping websites. Ask the user how much he expects his doctors to charge him ("Annual Medical Bill") in the next twelve months, then calculate how much he would pay to the doctors and to the insura…
I've toyed with adding some elaborate calculators. Last time I went through this exercise I built a rube-goldberg spreadsheet that let me plug in doctor's visits, major illness, deductible, premium, etc. and spat out a yearly number. It was just too complicated, though. Most people don't even understand what "coinsurance" is. I might add some pretty calculators later if the site gets some traffic.
That's exactly why you should add a calculator, so people can see how the variables interact.