There are several ways to loop a clip, but here a very simple one

Mechanical text animation preset from Adobe After Effects CS3

From Adobe's LiveDocs:

Super simple script that generates text layers and distributes them in 3D space.

This expression maintains the objects apparent size as it moves away from camera.
It's helpful for taking a flat layout and making a "multiplane" layout from it for animation.

Formatting a number with commas

Apply this expression to your 'Scale' attribute and it'll automatically 'flip' the layer in 3d space when the camera goes behind it. This way, your text will never be seen from behind, for instance.

Apply this expression to the opacity attribute and it'll disappear whenever it's flipped away from the camera. You need to have an active camera in your composition for this one to work.

From Adobe's LiveDocs

This expression is customizable, and you can change many things including: the radius of the cylinder, the overall rotation of the cylinder, the spacing vertical spacing between rows of the cylinder, and the amount of layer on each level of the cylinder.