I usually like elegant angel's trailers:
http://www.elegantangel.com/dvdTrailer.php?num=3694
http://www.elegantangel.com/dvdTrailer.php?num=3729 (Great movie/Trailer but trailer is WAY too long IMHO ... but totally works for their fan base)
http://www.evilangelvideo.com/title/1000008842 Jonni Darrko does beautiful filthy hardcore ... Check out any of the Trophy Whore titles
Now both of those are "better" known as DVD studios ...
I think the best web trailers belong to the companies that have been doing it for a long time and pay attention to quality of content. I have seen great scene trailers from RK, Bang, Brazzers, NS, Pron pros and of course ... your self included (and i'm not JUST saying that)
As far as the Lesbian Market i think Kissmegirl.com does the best trailer for what that niche is looking for:
http://www.kissmegirl.com/trailers/t...n-trailer1.wmv
and i have to say i still think this is the BEST College Invasion trailer:
http://www.collegehandjobs.com/ci6_trailer.wmv
xoxo,
Megan