I’ve been working with Blender 2.5 for a while now, and I have recently seen a need for a mesh itself, using the Emit value, to actually emit light instead of using the lamp object. I think that you can do this in Blender 4.9 using the Radiocity value under the Render menu, but I can’t find this or anything like it in Blender 2.5. Can I have some help, please?
Like RickyBlender said. For a bit of clarification, you access “Indirect Lighting” in the World panel, but in order for it to appear you have to turn on AO or Environment Lighting AND set the Gather method to “Approximate” (all this is in the World panel as well) – then the “Indirect Lighting” option magically appears. Increase the factor setting with Indirect Lighting to control how much your emitting materials light the stuff around them. (Of course, a mesh’s material has to have some kind of Emit value in order to do any emitting.)