I like the idea of the karma scale to weed out the idiots. How do you define a 'normal' dream, though? If a person is interested in UFO's and aliens, they could conceivably show up as symbols from the subconcious without necessarily meaning that the dreamer was abducted or visited. Dreams of gods and messiahs aren't necessarily divine visitations, either, but both of these examples can be pretty weird.
Of course, you'll always get the "I-want-attention" twerps who make things up just for shock value: "Hee hee, I dreamed I was shooting all of my teachers so now I'm going to do it." You'll also probably see someone acting out sexual fantasies. For the sake of not having to have ID checks, you'll want some way to remove these before they get you in trouble. I don't know much about web design, so I don't know what tools there are for this.
I'd definitely visit such a site, though. I'd even post a few of my more elusive dreams, especially the ones with repeating themes. For example, whenever I dream about driving, it's always long-distance driving, it's always around 1AM, and I'm always going to Indio, California. I've been by Indio (once), but I've never actually gone into that town. I don't know why I'm going there, only that I must get there.
Something from my dreams that stands out like crazy is The House. I think the house represents myself. When I first went to The House, it was a huge, colonial style building on a busy street. Once inside, all was peaceful and quiet with plenty of tall windows letting in the light. A work crew was inside cleaning things up from the prior tenant. I went inside the master bedroom where I saw a large Raggedy-Ann doll wrapped up in thick, clear plastic. I reched down to touch it, but a woman grabbed my wrist and said "Don't touch it. That's not yours." Then she showed me one of the furnished rooms, which was an art studio surrounded by windows that looked out on a forest with a river coursing through. It had all the drawing supplies I could ever want. The whole house was modern and in great shape...except for the kitchen.
The kitchen was more like a basement with pale yellow walls. One bare light bulb lights up the room, which is enormous. The floor is bare, cold cement. The appliances are antique and look like they're on their last legs, but they work. In the middle of the room and going halfway up the wall is a cement stairway that leads to a rickety wooden door. The dark yellow paint is cracked and flaking off. The doorknob is tarnished a dark brown. Sometimes the door is locked, other times it opens easily. Every time I go to open it, however, that same woman shows up and says with terror in her voice "Don't ever open that door! You aren't supposed to go in there!" She never tells me why, though. I know there's a darkness behind that door, but I don't feel that it represents death. It has more an aura of the unknown and unknowable than of death. I promised myself that when I have this dream again, I'm going to open that door.
Would this count as a normal dream?