Long take during opening titles.
For the entire opening number in the awful musical SONGBIRD - the camera stays on Streep and pulls back from the stage over the audience and then cuts to Goldie and Bruce.
There are many more famous long takes in movies TOUCH OF EVIL, THE PLAYER etc - but this one deserves to be up there.
http://www.imdb.com/mymovies/list?l=32397724