You should be able to click on the Sponsors link from the homepage to see a list of active vendors. However the "How did you find us?" is probably more powerful. They track the number of click-throughs on the banner, but I don't believe they track purchases from us.... so the How Did You Find Us is probably better anyway.
We appreciate the support though, and the only sponsor we have which we'd like you to go through the banner to buy from is TireRack, because we get a small percent kickback from them for every purchase made through the banner.