Amateur Allure is highly skilled at this angle, as the first link confirms.
http://www.amateuralluregallery.com/mgp3/aam-gra06/brokert.htm
http://galleries.spunkmouth.com/gals/?s=tabitha/wmv&t=11&rid=pp10530
A close up of the girls trying to look like they're enjoying it is quite a turn on.