2D Shadow Help

Okay, so I am making a semi-up down view game. Shadowing is very important to me, so getting normal mapping and the unity 2D shadow thing was very nice, but now I want to have a shadow at the feet of the character. However, when using the built in shadow, it becomes a ray that goes on forever. Is there any way to make a circular shadow? I do have one plan, but I also need to know whether there's any chance it'll work. Is it possible I can make a shadow sprite with some transparency? I would then have this sprite follow the character, and go invisible when unneeded with ray tracing. However, this seems tricky, and only partially functional, so does anyone have any ideas?