We just had a visit from VREX. They provide a variety of 3D options. They have one very low cost entry point for stereo glasses. For I believe $35, they have a pair of shutter glasses which connect via a wire into a pass through plug which goes between your box and the monitor cable. I don't know if you could put multiple of these in series or whether you are limited to one pair of glasses; you do have to live with being cabled to your computer; and I haven't actually seen these in action; but the price is very intriguing.
They are also looking at a very interesting technology for 3D on a laptop with passive glasses. It just requires the software to support an alternate scanline mode for stereo (i.e. even scan lines one eye, odd scan lines the other). They even claim to be willing to pass along the OpenGL code required to implement this mode. Anyway, their web site is www.vrex.com, and no I am not a shareholder or getting any kickback for passing this along. :-) Malcolm Davis