Stock photography sites are moving towards free, with either free samples (Photoxpress) or ad-supported images (Fotoglif, GumGum, PicApp). In an effort to encourage a broader distribution of its ad-carrying photos, Fotoglif is opening up a revenue-sharing API for developers. The first 500 people to sign up using the promotion code “Techcrunch” will get into the beta program.

The API gives developers access to millions of photos and related data, which they can mashup into widgets and other apps. The developers get to keep 20 percent of any resulting AdSense dollars generated by the images. Fotoglif pays the photographers 50 percent, and publishing sites another 20 percent, which doesn’t leave much for the startup.

The ads are little contextual text ads at the bottom of the image. They are not horrible, but they aren’t beautiful either. Attaching ads to stock photos is a good idea, but these companies still need to work on presentation. Maybe that is where a developer using the API can help.