As a heads up, some of my older demos (well, basically everything but the Quake 3 demo) are probably broken on newer browser builds at this point due to changes in the WebGL's API. (Hey, that's what you get for developing against experimental libraries!) Over the next couple of days I'm going to go back and fix them up (may even try to optimize the code a bit), so hopefully everything should be working again soon.
Until then, sorry for any broken code you may stumble across!
Update: So I've got all of the demos to stop throwing errors, but the Spore and Hellknight demo's aren't showing anything, even though they appear to load correctly. I'll continue looking into it, but in the meantime at least the Quake 2 and 3 demo's are running fine.