No avatar here
It'd be nice to use a real photo, but this is one forum where I like to feel I can be completely open about myself, and a photo would make me easier to trace, which would probably make me think twice about being so open. Also I'm extremely vain and would need to spend hours getting a shot I was happy with. Still, I appreciate the honesty of the people who just post a photo of themselves.
As for using a picture or design that isn't me, it's a great idea and I like a lot of the ones I've seen on WP. Shouldn't take 'em too seriously of course but I think sometimes they say a lot about the person. It's the first thing that hits me when I look at a thread, and to me it begins to feel as if it's a real photo of the being who wrote the post. One guy had a picture of David Tennant - seemed to have a look of serious inquiry in his eyes and I kind of felt that it was the Doctor who was talking.....of course I knew it wasn't really that, but it was a nice feeling anyway, it added a bit of interest and made me want to take part in his discussions.
I like the idea of using a real photo that isn't the real person - must be great for people who don't feel good about their own appearance, they can be anybody they want to be and I'll always remember them that way. Almost like a masquerade ball. On the other hand, it seems a shame if people have to hide their true appearance, I'm sure if they just had a bit more confidence there'd be nothing to be afraid of.
Choice of colours is often quite important too, you can't beat nice colours for a feelgood factor. Also avatars make it easier for me to recognise/remember people. Often I can't recall the username but I rarely forget an avatar. A picture is worth a thousand words.
I might upload one, if I get the time, but I'm stuck for ideas. I'd probably have to reject millions of designs before I found one that was really "me."