Old graphics papers don’t get enough respect nowadays; for example, Porter and Duff’s original paper is still the best place to get a good understanding of alpha blending (which too many people get wrong nowadays). There are many more gems to be found in papers from the 70s and 80s.  A while ago, I pointed out Pixar’s online paper library, which includes a lot of “golden oldies” (as well as good new stuff).  I just saw this great list of old papers on the codersnotes blog. I heartily concur with Kayamon’s assessment of the value of an ACM digital library subscription, though I wish ACM would find a way to go the Open Access route.  It’s not just a matter of expense; the registration wall adds a huge amount of friction to the process of finding information.