This is the image I used to back my Shadowdancer logo, at full size. I found the picture on Flickr, but I'm afraid I don't know who took it, so it's used without permission. If you took this picture and are reading this, I hope you don't mind. :)
I took it down to about -65 saturation, then adjusted the coloration on it to make it look a little more unearthly. I thought about trying to do a blur effect, and some other bits, to make it look more like the Astral, but figured it'd just turn into a blob of grey at the size the icon was at.