"http://www.hdrlabs.com/sibl/archive.html

Some of these are rather large. You can't use em commercially tho, but you can use em for your personal renders."

IIRC, most if not all of the SIBL sets have three images, one for the background, a smaller one for lighting and a blurred one for reflections - very convenient. 

"Democracy is a pathetic belief in the collective wisdom of individual ignorance." - H. L. Mencken