Some of the resulting innovations have transcended the pejorative 'gimmick' to become important facets of cinema. Wide aspect ratios are taken for granted in this time of 16:9 HDTVs, but originated with non-standard formats like Cinemascope that were originally implemented by competitive theater operators looking to out do each other as well drag customer eyeballs away from the Radiation King in their living rooms.
Few other cinematic gimmicks were as classy or successful as Cinemascope, but they definitely added a cheesy, carnival like atmosphere of spectacle. The undisputed king of such contrivances was William Castle, director of House on Haunted Hill, 13 Ghosts, and Mr. Sardonicus. To add some extra zazz to the scary bits of his films, he would set up elaborate contraptions in select theaters. Haunted Hill famously had a fake skeleton fly over audiences' heads at certain times, and The Tingler boasted electrified seats scattered randomly through the theater. Other films would have 'nurses' on hand to treat fear induced heart attacks, or micro-intermissions before the climax so that anyone too scared could leave and get a full refund (also a public shaming for their cowardice).
While modern moviegoers are a little too sophisticated (cynical?) to be taken in by plastic skeletons or hollow boasts of death by fright, such practices have fortunately not faded entirely away. The director of Indian horror film, Phoonk 2 (Electric Boogaloo?), recently offered $10,000 to anyone brave enough to watch the movie alone in an empty theater. Plus, as mentioned above, Hollywood is making pretty much anything that it can think of into a 3D movie these days. (I miss the '80s, where you could apparently only use the process on the third film in a franchise.)
Sadly, the director of The Human Centipede (First Sequence) has not announced any sort of free vomit bag promotion at theatrical screenings of his film, but after coming up with such an outlandish and disturbing premise, everything else (likely including the film itself) will have to play second fiddle. Watch the trailer below:
Is it a spoiler to show that the centipede is completed at some point in the movie? It will surely steal some of the suspense from the cat and mouse games between the crazy German surgeon and his nubile victims, but it would be a far greater crime for us to sit through a mediocre horror/suspense film called The Human Centipede about a mad scientist trying to create said human centipede without actually having any human centipede action. I'm not buying a $10 ticket to The Human Centipede to see people narrowly escape being turned into a human centipede. The rest of the film is just (for lack of a better term) foreplay. To use another example for context: does anyone go see Friday the 13th movies to see a bunch of people narrowly escape getting murdered by Jason Vorhees? No. So let's not pretend that we're going to The Human Centipede to see if the characters manage to escape when we really just want to know what happens when the middle one has to go [insert bodily function here].
Also, you all have to go see it so the director can make The Human Centipede (Full Sequence) which may have up to a dozen(!) poor bastards sewn together.
Update (2/9): To clear up some confusion that this rambling, barely coherent post has induced in some of you, I consider the centipede itself to be the movie's gimmick. It's a premise so unique and outlandish that I have absolutely no problem with the construction of an entire movie (maybe two) around it. Plus there is the carnival freakshow aspect to it. Anyways, I don't have to explain myself to the likes of you.