I wish I had been a member when the first Zenni thread came up. I've been using them for 4 years. My DW and I have bought almost 30 pairs of glasses from them. I can tell you that SOME of their frames are cheap, their SS and Ti frames are great and extremely lightweight. My only gripe with their selection is that don't offer prescription sunglasses in which the lens itself is corrective. All of their sunglasses (as of last December) had a corrective lens mounted behind the tinted one. Other than that, I love their stuff. I have glasses everywhere: in the house, cars, my EDC bag, my fledgling BOB, even a spare pair in my desk at work. I've only managed to break two pair and that was through carelessness on my part. I have glasses for every type of dress situation and even some in different colors. (nothing crazy, but sometimes one does want a hint of color...)
All in all, I think Zenni provides a fantastic product for the price.

-Jason