Stock agencies will market your work for you and take a 50% or 60% cut, well worthwhile because these agencies will find markets you never thought of. Getting listed with an agency is highly competitive. You must submit an initial portfolio of hundreds of images to be even considered. Many of these agencies now also market work on CD-ROMS such as PhotoDisc. Here are some of the players:

Alamy has emerged as the online giant of stock photography, with over 35 million images. The search engine is fast and efficient.

Ambient Images features in-depth coverage of California and New York.

AnthroArcheArt.org features royalty-free archeology images from all over the world.

Black Star, a photojournalistically oriented agency in business over 70 years.

Comstock has been around for decades. They boast over 2.5 million images.

Corbis. Owned by Microsoft, Corbis is one of the largest photo agencies in the world.

Fotosearch is a clearinghouse for millions of images from many large agencies. Lots of great stuff.

Getty Images. Along with Corbis, Getty is one of the largest international providers of visual content in the world. The two mega-agencies have redefined the stock industry.

PhotoAgora is a small but elegant agency based in Virginia.