http://www.comparethemarket.com/
http://www.moneysupermarket.com/car-insurance/
to name a few...
I understand that this was a legal issue due to the insurers (but even so, they only launched a year ago...) but what is it with American companies that they just don't seem to get the internet?
Comparing price of auto-insurance is really no different than comparing the price of flights, travel insurance, cars, houses, whatever. It's a product/service and it is not going to be one size fits all. Some insurance companies will be a better fit in terms of price and options available, so insurance companies that are competitive will actually get more customers by being on the comparison sites.