What are some of the best free stock Photo Sites?

I am an avid Photoshop user, and I haven’t really found a good free stock photo site (I’m not even certain there is one). Stock.xchng is the best I’ve found so far, and it is above average, but I was hoping to find a better photo database.

Apart from what is already suggested maybe try: http://www.photoxpress.com

They allow you do download one free image a day, which isn’t much but it may help if you are just looking for a specific image.

Hope that helps!

Mitsubishi Evo vs. Subaru Impreza – Top Gear – BBC