I created this shader to add ambient lightning to my models.
I used a spherical environment pic that I processed in HDRshop (http://www.debevec.org) to create the enclosed diffuse lightning picture. 
The normal mapping just acts more or less like a spherical environment except that the mapping don't change with the point of view.

Francois Rimasson

RIMASSON.FRANCOIS@wanadoo.fr
http://membres.tripod.fr/rimasson