Some people have used gems in their home base for lighting at night, but I don't know if they would work well over a large area. You can bump up the gamma in the graphics options, as long as that doesn't make the screen too bright outside during the day.
I occasionally load an old save to check something or get a screenshot, etc, but am not currently playing DD. I'm planning on going through D2:DC eventually with a different character build, and may play DD again before D:OS comes out (I don't normally replay games, especially when I still remember them well).
