I've always been a fan of staying until the last credit has rolled off the screen, I think it started when my "Big Sister" was talking a film class in college and she mentioned to me that was one of the requirements (one that most of the class ignored, BTW). Later it became an answer to "where did they film that
James Bond sequence," and "what song (or piece) was that and who was it by?" When my brother took a film class, it was to see if the same guy who was the foley artist (?) in the last movie had the same job again for this film.
Then Pixar came on the scene you had
to stay for the 'out-takes' (and recently for the "OMG, I've know him/her").
Now according to Yahoo! News it seems wanting people to stay has gone mainstream
“As several recent movies demonstrate, filmmakers are getting creative with their end credits. They're starting to add a flourish that's akin to an exclamation point at the end of a sentence, giving viewers a reason to stay a bit longer in their seats for a memorable treat.”
Not sure how the theater workers who have to clean the room for the next showing feel about this – at our showing of "Stardust" we were the last two to leave, giving ample time for the two workers to practice their Can-can
routine to Offenbach's famous Galop Infernal from "Orpheus in the Underworld" before they could pick up the discarded popcorn tubs and soda cups.
Then again, sometimes there is something to be said about leaving 'early':
“Shoot 'Em Up's" end titles hark back to scenes from the movie. Credits in two bullet holes pull back to reveal a pair of breasts, referencing the lactating hooker played by Monica Bellucci.”