PhotoDopers, stock photo sales sites?

I have a customer who is desiring to make a few bucks via sales of stock photos and the like. She is partly disabled so she is looking for something she can do as her health permits. She does not like the idea of retiring/going on disability so young (33) and has always been into photography as a serious hobby. Apparently she has been doing well in local/regional contest submissions like county fairs and such so she must have at least some ability to use a camera.

She is looking for either places that may outright buy pix or preferably something that provides ongoing comissions for anytime one of her photos is purchased.

Are there any websites that offer that type of arrangements? If not are there any other avenues that photographically inclined dopers might be able to reccomend?

Shutterstock and iStockPhoto are the biggest players in the ‘microstock’ business, which means subscription-based, royalty-free stock photos. The artists are paid a small amount every time a subscriber downloads one of their pictures, but doesn’t get paid royalties if the picture is used. The photographer retains the copyright so she can still license the pictures separately if she wants.

If you’re good (both sites have high standards) it can be very rewarding for a hobby photographer. Some people even make some serious bank, but you have to shoot a lot of stuff of in-demand subjects.

[sub]Disclaimer: About a billion years ago I did some contract software development for Shutterstock for a few months[/sub]