Thanks to Steve "PudgyM" DeRose, I now have two destinations in my bookmark file that will doubtless cause me hours of lost work. Check these out:
EFANZINES.COM: an archive of electronic Fanzines (some scanned from paper, some not), in PDF format, going back quite a ways, from a large number of sources. Also SF convention photographs, program book covers, fanzine cover art, and various visual efluvia going all the way back to the early fifties. This is a fantastic archive.
VISCO: the Visual Index of Science Fiction Cover Art. An attempt at a visual archive of the covers for just about every pulp SF rag that ever breathed life. An amazing collection, still building as we speak and recently added a gigantic ASTOUNDING/ANALOG collection that would make an excellent reference source for the idly curious.
Enjoy! I know I did.