Thanks for the shout-out, Travelin2. Yup, you're talking about the "Fresnel Wide Angle Lens" (available at www.CampingWorld.com then search for "wide angle lens") that most big RV's use in the rear window, and that many VX'ers here on this forum use in their rear window as well (myself included).
I have seen other Europeon-style blind-spot mirrors that suction-cup on the interior side of the windshield near the windshield pillar, but I have no actual experience with them. They can be found at www.AutoSportCatalog.com website, then do a search for "spot mirror".
EDIT: Although no spot mirrors were found at www.HerringtonCatalog.com, they do have some cool stuff.