How to draw a texture in worldspace and move said texture's position?

I figured out how to create a ground targeting effect similar to Dragon Age: Origins and Guild Wars 2, but I just need a texture to appear on the ground. Does anyone know how to get a texture to be drawn in world space and update its position while in the world?

 

Raycast down onto the surface where you want it to appear. Use a Plane with a texture on it at the hit location and use the hit normal to adjust its angle if the ground is not flat.

http://docs.unity3d.com/ScriptReference/Physics.Raycast.html

 

Or use a projector. Or a world space UI image.

 

Can you specify sizes of textures/images using a projector? Because from what I understand, based on the manual, is that the size is based on the camera frustum and not the mouse's raycast hit point?

 

It depends on the settings in the projector. In terms of mouse position - you can raycast the ground and position the projector over top of that point and face it straight down.