Hey folks - I'm not associated with this site in any way, but I use it often.
StockXchange - stock.xchng - the leading free stock photography site - tons of commercially licensed photos, free to use. A few require permission from the owner prior to downloading, but most may be downloaded without. I like the site because it's categorized, the servers are relatively quick, and the full size photos are really high resolution. I use this site a LOT. I didn't see a previous post for this, hope it's appropriate for Pimp The Link.