Displaying text on a GameObject

it's not possible to procedurally draw text on textures however there is a component for drawing 3d texts. this component is called "3d text mesh" and will create a 3d text mesh for you so it's a mesh itslef and it's not drawn on a surface of another object, you can put it on planes to simulate text drawing on the plane but if your object is curved then it's not possible to simulate it in this way.

i did not tried but if you use GUIText instead of unity gui and render the camera with GUI layer on a texture then it might be possible to draw text on textures in this way (not tested).

hopefully the next gui system that UT is working on will support rendering GUI on textures. sometimes it's really usable mostly in simulation software for kiosks and mobile phones and ...