But what about the thousands of other movies (made since 1978)?
Well, the good folks over at The Verge have created a web search that will save you precious minutes of your life by allowing you to search any movie title to find out if there's a post-credits sequence.
Yes, never again will you have to find out who the assistant monkey wrangler was on Jay and Silent Bob Strike Back only to be disappointed when there's nothing at the end of the credits (actually, there is one on that movie).
Honestly, it's kind of more useful as a way of finding out about post-credit sequences in movies you wouldn't even think to search. Because it has an auto-fill function, you can type in a single letter and bring up all the movies starting with that letter that do have post-credits action.
That is how I now know that there is a random Japanese girl waving to the camera after the credits to Lost in Translation, and a shot of Skeletor totally ripping of The Terminator at the end of Masters of the Universe.
You can search it for yourself here.