Piers anthony was my favorite author when I was a young one. Incarnations of immortality was what got me started on them
I read all of them except the god one, which i believe was the last one. His space tyrant one is good too.
Aura photography is called Kirlian photography. If you throw that into google you're likely to find many pages with lots of information in it. From what I remember reading about it, most aura photography is fake. This was a few years ago, but at the time the biggest object they could get an aura image of was the thumb. It may have improved since then, though.
If you start looking into "spiritual technology" you're bound to find out alot about the Monroe institute. Through that you can learn about Hemi-sync technology and even lucid dreaming machines and trance goggle type things.
Alot of it makes some sense, for example: Hemi-sync technology is based on the idea of our brain waves. Alpha and beta waves and such like that.. their frequency is so low that our brain can't even normally comprehend it, however hemi-sync supposes that you can play one frequency in each ear, and because of the way the brain registers sound it will register the "Difference" of them.. so if you're listening to a frequency of 200 and 205hz, you're hear a frequency of five which is equivalent to the brain's Theta stage which is a light sleep stage. That kind of technology is also called Binural beats..
I have a link to a "Brain wave generator" that creates binural beats and such, and I know there's sites online that sell kirlian cameras/accessories.. just be careful about that, they can run some money and it would suck to get ripped off.
And as for aura colours, 'they' say that since red is the lowest vibration is more earthly and material, while the highest vibration is purple which is more spiritual. There's alot of information about that sort of stuff online, and who knows if any of them can even see auras?
http://kirlian.org/kirlian.htm