LightRigger is a freeware Maxscript lighting utility for Autodesk's 3ds Max.

The LightRigger script runs inside 3ds max 3-2008 and provides a draft-quality, global illumination lighting system for the default scanline renderer.  Unlike full-featured global illumination renderers, LightRigger uses standard 3ds Max lights and components to simulate only the diffuse interreflection component of global illumination.

LightRigger's main advantage is speed, both in setup and rendering.  The core principle on which it's founded is the well known "old-school" approach of using a light dome or rig, but LightRigger takes it much further.  Using a little-known behavior of the default scanline renderer, LightRigger is able to convert Light Rigs into Shadow Rigs, which add shadows but no light at all to the scene.  This is what allows multiple Rigs to work together in the same scene....something that is impossible with traditional light domes.

LightRigger is also unique in that objects illuminated with its Rigs are able to move and animate freely, rather than be restricted to the scope of a single, large light dome.  The amount of control in the LightRigger system is unmatched, allowing you to focus on your scene instead of continually managing a loose group of lights.

The best way to understand LightRigger is to see it in action.  Click on the Demo Video link to see a few viewport screenshots and two narrated demonstrations.