Simple, useful – one for the bookmarks. Unsplash is a Tumblr blog that does nothing more than collect images that would be suitable for your next startup or product’s splash page.
Simply browse for the image you’re after and click download. You’ll find full attribution info under the images.
If you’re looking for something more in depth with search functionality and more, find a great list here.
Unsplash is a side project by the guys at Ooomf.