Karl Kleine has collected a nice array of historic documents in computer science, including the original Fortran manual, dated 47 years ago.

Linked from there is Al Kossow's manual collection, which covers ancient hardware, including the IBM 1620. Believe it or not, my high school had one of these things, with the delivery invoice still in the desk drawer, showing it had been dropped off at the school before I was born. For even more old-time fun, Al also has the The Minicomputer Orphanage on his site, complete with pictures and descriptions. All in all, a big blast from the deep past.