This suite of tutorials is largely aimed at pre-UT3 versions of the Unreal Engine. However, some of the information, particularly in the 'Theory' section, is universal regardless of the Engine, or game, used.

If you're a level designer interested in learning more about lighting, I'd reccomend reading through the entire work.

Unreal Lightings
Original Author: Gui
Translated from the French: ArcadiaVincennes
Original French Tutorial at Eclairage

Many thanks to Gui for allowing me the opportunity not only to translate his work, but also for allowing me to host it here. Merci Bien Gui!