iStockphoto is one of the most important Microstock (selling your photos/media online) sites today. Here's a snippet of the article:

Today we'll be reviewing iStockphoto, another one of the big players in the Microstock business. Find out why millions of people love this site and why it could help you to even monetize your audio files!

Website
iStockphoto.com

Support
+00 800 6664 6664 (only available for: Australia, France, Germany, Ireland, Italy, Macau, The Netherlands, New Zealand, Spain and UK)

Monday to Friday, 8am to 5:30pm
Mountain Standard Time (MST)

Business Model
'iStockphoto works on a system of micro-payments, which allow you to purchase images in quantity. Images cost between 1 to 20 credits per download, depending on the file type and image size.