I did some shadow casting tests. I don't know if there's better ways to do this with some plugins.
Drag lights and objects around with your mouse. Add lamps with mouse middle, delete with mouse right and when you are ready to calculate the shadows, hit enter and wait until it's done. To reset everything hit spacebar.
In this version light sources are casting light. Try to create walls to see how it works.
This one is using opposite method and is a bit heavier to calculate.
This one is casting realtime dynamic shadows. I made it really light and the cool thing is that it also works without WebGL. It should run around 60FPS.
This one is a bit experimental Ambien occlusion for 2D.
Let me know what you think...