Scott Wardlaw has created a sticker generator program for LEGO models. The program takes bitmap images and converts them into files that can be used in LDRAW and MLCAD.
The top photo is a screen shot of the program showing the bitmap image to be converted. The bottom photo is the converted file, used as a sticker on a CAD-generated model train. (Click on both images above to see more detail).
I haven't used this program; however, if it works as advertised, it'll make a nifty addition to LEGO designs.
The program download page is
Scott would appreciate any feedback you have for his program.