Earlier this week I came across Every "Itchy & Scratchy Show" Ever, and went to see if its creator MrBestDeni had made more "Simpsons" stuff. Turns out he hasn't done more YouTube videos, though he's on Vimeo now. Anyway, in the "Simpsons" video experiment below, fellow YouTube hero Romain Vuillemot runs 130 episodes of the show simultaneously, in a grid, for about three and a half minutes. The result is an extremely weird visual experiment -- we get to see how the opening credits differ between episodes, and also between seasons. Then when the credits finish rolling, it's just overwhelming visual cacophony, mercifully cut short before total brain meltdown. There's no sound here, so it's easy to watch for a minute or two without being caught at work (ahem).
-Top to bottom: each row shows a season (from season 1 to season 10)
-Left to right: each column shows an episode (from episode 1 to episode 13)
A total of 130 episodes is displayed, framerate is 25fps, thumbnails have been captured at 80x60px
While it seems that some of the variance occurs due to the videos starting with very slight different bits of a blank screen at the very beginning, a lot of what you see is due to real variations in the opening sequence (well worth a read), which famously contains variations from episode to episode, as well as from season to season. Each sequence includes at least a chalkboard gag, Lisa's solo, and a couch gag -- and later seasons include a billboard gag too. Also interesting: a collage of Springfield assembled from shots in both the original credits and the new HD version.
Note: I originally miscredited this as being MrBestDeni's work, then noticed my mistake today after 27,000 people watched this video. Turns out MrBestDeni just commented on this video, rather than authoring it. Fixed!