Attached Link: http://developer.valvesoftware.com/wiki/Creating_Normal_Maps#GIMP

This is a nice tool, but I see few options, or switches. Maps are too low res for some things and it is reversing some depths. I only used it on one project I will have to see what can be done with it. I am checking out the nvidia ones listed. ATI has one for using from 3d objects...haven't tried to see if it can read 2d. Altho I got a nice map from corel photo-paint performing similiar technics it took too long and too many steps. I would suggest using the gimp w/ the plugin available for normal maps. Very nice and quick. Gimp will currently only support 8-bit tho. (Don't know about betas)Info and links here, as well as other related info.

No need to think outside the box....
    Just make it invisible.