iStockPhoto
Zeldman points us to iStockPhoto.
iStockPhoto is a collection of over 26,000 royalty-free photos, illustrations, and multimedia files created by a growing international community of artists. The site adds around 1,000 new royalty-free photos each week.
You get 2 free downloads for signing up (or at least I did) and you can purchase 40 download credits (I'm assuming 1 credit per image) for $10. Not a bad deal if you need stock images for a site.