One of my newest obsessions
Wikipedia:Kinetic typography, is the technical name for "moving text," is a study of Communication Design in animation work involving text. The first part of the name 'kinematic' derives from the word kinetics (i.e. the motion of objects) and the second part of the name is the art of typography. This text is presented over time in some sort of way which can imply or evoke certain emotion. Some commonly seen examples include movie titles and credits, end tags, on web pages and other entertainment media.
A few examples
And the link from where i ripped it off (shamelessly)