i threw this together over lunch:
you'll notice that the camera is rotated and that the beam is 'facing' the camera. the red spheres are used to calculate start and end points.
there are still a couple minor problems, but works okay for the 45 mins I put into it.
you can move the red dots around, or the camera, and the beam always looks good, starting and ending in one of the dots. this uses the 'billboarding' idea.
you could easily modify this to use multiple plains using the 'emitter' approach found elsewhere in the forums.
i'll do some touch ups and post some code tomorrow if you're still interested.
cheers.
-= i only do what my rice krispies tell me to do =-