Father Ted boxset - couldn't survive without this, but I would miss the rest of the comedy collection such as South Park, Time Trumpet and Arrested Development.
Blue Planet - Bit of culture, innit? And pretty addictive.
Hitchcock boxset (North by Northwest, Stage Fright, Dial M for Murder, Strangers on a train, etc) - Essential viewing
Batman Begins - Can literally watch this any day of the week.
O brother where art thou - See above