The Image Permanence Institute has a new website called The Graphic Atlas, which is a resource designed to help in identifying printing techniques from the earliest printed images right up to the present. Do the "Guided Tour" and choose a printing technique for a sample, or try the "Identification" tab for a detailed explanation of each method. The site is well-designed and some of the graphic display is quite marvelous. You can zoom in on the paper-fibers, look at the printed surface edge-wise (highly enlarged, of course), or look at the way the gloss or matte on the image changes as it is turned angled toward or away from the light.