I used to visit the NYC branch all the time when I was resident in or engaging in research in that city.
Some programs they have that aren't in circulation and that are of interest:
-A viewable episode (and others that can't be seen) of a version of Information Please that isn't in any standard reference
-Several episodes of the NBC run of Let's Make A Deal, including one from the primetime run
-A Break The Bank episode from 1949
-An episode of Pantomime Quiz that, from context clues, seems to predate the network runs of that program
-An episode of On The Spot, for those curious to see a local game show from the mid-1980s
-Sample episodes of several short-run 1950s game shows, including Anyone Can Win and Ask Me Another
And, to add to a previous post: they hold two color episodes of Concentration, including one that is (if I remember correctly) the last episode from their last Tournament of Champions.