Apparently, there is some sort of special holiday today, and according to a memo from The Ministry of Consequences it is about Easter Eggs. No, not the chocolate ones, the hidden places in software and DVDs.
The best guide to DVD Easter Eggs is naturally http://dvdeastereggs.com/ which catalogues how to access the hidden features on DVDs.
One of my favourite Easter movies which has an Egg is "The Rocky Horror Picture Show" which presents the opening scenes of the movie in black and white, until Brad and Janet enter the castle to "The Time Warp". (It is too an Easter movie, if only because I say so)
BBC has an article on Easter Eggs in software and DVDs as well, including "Spider Man".