Sorry Shawn, as a native New Yorker I am obligatorily clueless as to what to do here. If by chance though you happen to be visiting either Forbidden Planet (NYC's best comic book store) or The Strand (the WORLD'S biggest used book store - 16 miles of book shelves and counting!) either today or Friday, drop me a line - I work upstairs from these 2....
Oh, and be sure to hit the Greenwich Village bars tomorrow night - quite a scene...
Okay fine, and some additional: The Museum of Natural History on 85th is world-famous, and easily a full day - catch the planetarium show! If you're into theater, a Broadway show is a no-brainer - there's a booth called TKTS on the traffic island at 47th and broadway - they open at 3PM, and sell half-price day-of tickets for whatever hasn't sold out yet for that night -- a great deal! And of course, like others have mentioned, the Met, the Guggenheim, the Museum of Modern Art (MoMA)..... and yes, the Compleat Strategist (at 11 East 33rd Street) IS the coolest gaming store EVER....