There's this study floating around the internet recently - I first heard about it on the fabulous Poly Weekly. The long and the short of it (ha!) is that women in Australia were shown computer-generated images of naked men of varying heights, body types, and penis sizes. The sensationalized version of the results is, "OMG women totally love giant dicks."
The actual version of the results of the study are, "yeah, penis size had a marginal effect on gauged attractiveness. But overall, height and body type were more positively correlated to perceived attractiveness."
The main issue I have with the study and the ensuing hoopla
was the fact that the women were shown computer-generated images of totally naked dudes. And then they were asked to quickly rate perceived attractiveness. Which, the chances of something like that happening in real life are pretty slim to none. I think the only time I've ever been in a room surrounded by naked men was at the gang bang. And then nobody was holding a survey up to my face like, "on a scale of 1 to 10 what do you think about so-and-so?" Usually when I meet dudes (even when we're meeting with the expressed purpose of seeing each others' genitals that same evening), we have our clothes on for a bit first. So it's impossible for me to rate "attractiveness" based on his dick size right away. I've been surprised on both ends of the dick-size spectrum before. Guys who I thought would be reasonably well-endowed turn out not to be - guys I would never imagine having monster cocks turn out to have them. In either case it's always fun finding out. And I wouldn't say at that point it factors largely (ha!) into whether or not I find the person attractive.