I probably have about 5000 pictures that I've gotten from the www over the years. About 2500 of these are in my screensaver at any one time. One of my friends says I should charge people to see my screen saver.

Mostly tasteful nudes and light bondage pics.
There is one folder of heavy bondage pics that I put in the screen saver if I'm not expecting company.

The only real criteria is that I like the photo. I use PhotoShop to crop or resize them for use as avatars.
If you see one you like just ask and I'll send it to you in the full sized or avatar version. Alternatively, if you have a photo you'd like resized to use as an avatar, I'd be pleased to do that for you.
"My Love, My Lord" has done just that. She asked me to share a shot she really liked, then sent me several very nice pics that she had run across on the internet. The most recent one will be my next avatar. I really like it.
I never charge for them and I happily credit the photographer andor model if I can, I just enjoy their beautiful work, so copyrights are not much of an issue. If anyone contacts me about an image that belongs to them, I appologize and delete it.
If you're not familiar with The Stockroom or Steve Diet Gedde's photography, go here:
http://gallery.stockroom.com/ to see some wonderful fetish photography. There's no sign up or purchases involved.