There is an interesting feature in the camera of Galaxy S phones, called Add me. Using this one can take photo of a person sitting in two postures in the same frame. (A normal photo is taken, the person in the photo can change his posture and again when clicked the new posture along with original is taken in same picture creating a double/twin effect) Are there any Apps in market for this or has any one ported this to Sony Xperia X8?
There is an app called "Twin Me!" in the Google Play. It does exactly what the Samsung Galaxy S "Add Me" feature does.
Even if not exactly the same thing, hearing your description makes me instantly think about Cinemagram, an iPhone app that should be ported to Android really soon.
In a nutshell, the application grabs a little video of the chosen subject and then gives the possibility to "animate" a portion of a selected frame. The effect can be both amazing or chilling, depending on the subject and the skill of the operator.
This is surely a nice app to have on the phone, and if you are a Harry Potter enthusiast you could also try to make a newspaper out of it :)