Dave over at Imaging-Resource has compiled a set of Ofoto Albums containing their standard test samples from no less than 30 digital cameras, via links on the Imaging-Resource page you can select and order prints of these test images. If you've not joined Ofoto before (or you still have some left) you can use the 50 free 4 x 6 prints for some of these samples. Kudos to Dave for a great idea.