ClipDis for iOS (free) is about as different from the typical messaging app as you can imagine. You type your text, and the app replaces every word you type with a clip from a popular movie. You can then save the clip to your camera roll, send to Facebook, iMessage or mail it, or send it to your clipboard to paste anywhere.
The app works pretty well... it indeed found clips from movies to replace my words. When I gave it something tough, like "Merry Xmas from TUAW" it grabbed a static shot of the TUAW webpage, and a synthesized voice said "TUAW". That's pretty clever. Here's a video example of a similar holiday sentiment:
The developer says he hopes to make money on the app by featuring movie clips that studios want to promote. But the app is free for users. You can use the app from the ClipDis web page, or from the app of course. If you use the app, you need a free account, but your email is only used to identify you, and your name won't be sent to third parties.
This is certainly a different messaging app, and the compilation of the clips into your personal message happens in a couple of seconds... unless the ClipDis server is being overused as it was this afternoon. It may very well be that the ClipDis team wasn't expecting a lot of traffic, and if the service doesn't scale well, it's not going to be useful at all.
ClipDis requires iOS 7.1 or later. It's not universal, and it is optimized for the iPhone 5 and 6 series.