In the Dec 2009 issue of Car and Driver, there's a nice write up about 3 major players in extended warranty - Mogi, US Fidelis and StopRepairBills.com, also a glimpse of how they sell these contracts.

Here's a link from "St. Louis Today" if you wanna check out the article Car and Driver secret shopper stings area service-contract brokers | The Savvy Consumer Blog | STLtoday