Ive seen in a few places images made using a technique called HDRI (i think?). Anyway would some please let me know what this technique is, what it can be used for and how to use it in blender?
Well, you can use a fake HDRI in Blender witht he use of eeshlo’s script. Do a search for that here.
As for actial HDRI, you will need to use a raytracer, such as YAFray. Here is a thread at www.yafray.org that explains it for you:
BgDM