I think Mr Stiff was actually one of the first porn search engines on the web, but don't hold me to that. It's a man-themed hub, but I will be straight up with you: there are plenty of straight videos here even though it's all about a cartoon dude looking to get his dick hard.
Head on over to the site, type in your keyword and get presented with a large array of videos from numerous sites. You'll find that the homepage also has a few suggested tags, one of which was 'gay faggot master' - it made me laugh, but it seems to be pretty damn popular. No idea how that came out!
Anyway, MrStiff.com also has an image search feature if you're looking for photography. The results of both types of material can be filtered by relevance, upload date, rating, number of views and finally, duration. The display of content here isn't the best, which is why I can't rate it as a top-tier search engine.