Cross your eyes and prepare for eyestrain, here comes the WebGL stereogram. Drag with LMB to rotate, drag with MMB to pan, wheel zooms, shift-wheel scales model.
The demo uses glScissor and glViewport to restrict drawing to one side of the viewport, then draws the scene to the left and right sides with the camera offset slightly. The camera offset is along the right-vector of the camera and you can get it by finding the normal of the camera up and look vectors. Basically
right = cross((lookAt - position), up), then
leftEye = position - (sep/2 * right); rightEye = position + (sep/2 * right). Then you render to left viewport from
rightEyeand to the right viewport from