When I wrote the post for Space Time Continuum I recommended a Science Fiction collection put together by Turner Classic Movies. They feature four movies each and CPL has several other of these thematic based sets. There's lots of good viewing here, with the Murder Mysteries, Sci Fi and Horror compilations being particularly strong. So if you aren't watching the Olympics, or just need a bit of a break from all that reality, grab one of these and away you go.
Sc Fi: Soylent Green, Forbidden Planet, 2001: A Space Odyssey, Time Machine
Horror: House of Wax, The Haunting, Freaks, Dr. Jeckll and Mr. Hyde
Murder Mysteries: Maltese Falcon, Big Sleep, Dial M for Murder, Postman Always Rings Twice
Best Picture: Casablanca, Mrs. Miniver, Gigi, American in Paris
Wsterns: Wild Bunch, McCabe and Mrs Miller, Jeremiah Johnson, Train Robbers
Broadway Musicals: Show Boat, Annie Get Your Gun, Kiss me Kate, Seven Brides for Seven Brothers
American Musicals: Band Wagon, Meet me in St. Louis, Singin' in the Rain,Easter Parade