I agree, VNC+JPEG is a good fit for this kind of thing. I posted a comment recommending TurboVNC earlier, but it looks to be hidden. It compared favorably with

I agree, VNC+JPEG is a good fit for this kind of thing. I posted a comment recommending TurboVNC earlier, but it looks to be hidden. It compared favorably with TigerVNC when I tested both. VirtualGL support is baked right in, though of course you have to first set up VirtualGL itself. That'll allow you to use the GPU on a headless machine and share it between users. (with some caveats)