I only have a few minutes tonight but I want to share the news that Google Book Search now includes old issues of what seems to be about ten different magazines. Unfortunately, Google intends that access to the magazines only turns up when a Google search is being performed on a subject mentioned in one of the featured magazines. There's not really an easy way to find out how many magazines are in the data base at this point, but Search Engine Land has kind of a road map for those wanting to read complete back issues rather than just an article or two.
The procedure described really works well and led me quickly to this page from which I can read whole issues of New York Magazine from certain years between 1965 and 1995.
Now I'm warning you that this can turn into another time-eater, so be careful, be very careful.