Cropng

does anyone know any graphic programs, i.e. photoshop or whatever, that have a tool that crops to the outline of an image... basically what i want to do is get a picture, drag a marquee over it and then use the tool that crops to the edge of the main picture in the photo

does that make sense?

if anyone can help can you please tell me a suitable program and where to get it if possible

thanks alot

peace-:D