iStockPhoto

Though iStockPhoto been around since 2000 and is the leading "micropayment" stock photo site, they seem to be getting some renewed buzz lately. Acquired by Getty Images in February, iStockPhoto sells royalty-free images for as little as $1 and offers photographers the opportunity to submit photos for stock usage (debates on the merits of that practice rage here and here). Worth a spot on your resource list, if it isn't already there.