Free stock photos at Kave Wall Stock. Most of the photos look to be about 800x600 and there will supposedly an option to buy higher-res photos on the site. Might be just the thing for filler or final art assets.

Nice link - those are some of the better (free) fire/smoke shots I've seen. If anyone's looking for more free photo sites check out my link page: http://developer.chaoticbox.com/resources.php (I'll have to add this site!)

http://www.sxc.hu