Interesting question, and one I hadn't thought much on before. Like a few others said above, I can get teary over a movie or a song or a news story (yesterday's about the homeless schizophrenic man calling out for his father as he was being beaten to death by police comes to mind), but I can't recall ever crying over a photograph, at least not over one not of a loved one. Of course I have found some photographs to be very moving, and many of them are seared into my mind. For instance, I find Weston's last pictures to be powerful and poignant, but I wonder if I'd feel the same way if I didn't know so much about his life and about his sickness toward the end.
On a related note, if I could ever get anyone to weep over my photos it would make me very happy.
Here's a pretty melancholy set (put on some sad music and view it as a slide show):