You can sell your photographs through Shuttercock.com. There are stringent guidelines, but if you're a really good photographer this is a good option.

Here's a blurb from their website:

Make your creativity shine at Shutterstock and watch your earnings grow. Get your work seen by the high-volume buyers who prefer Shutterstock. It's free to contribute and you'll earn $0.25 to $28.00 per image download. Learn how it works here.