Some of you may have seen this before, but I thought it was worth sharing with my fellow texture modders:

http://zarria.net/nrmphoto/nrmphoto.html

Basically, instead of using a plugin and building the normal map from the image or a model, you capture the photographic references needed for the normal map on the spot when you shoot your base texture picture. Maybe not always an applicable technique, but something to certainly keep in mind if you're out and about snapping photos for environmental textures. Just remember to bring a flashlight (and maybe a bit of shade, if it's really sunny.)