This does a couple of things -- rendering TeX, and plotting graphs. As has been pointed out, [MathJax](http://www.mathjax.org/ http://www.mathjax.org/) is real

This does a couple of things -- rendering TeX, and plotting graphs. As has been pointed out, [MathJax](http://www.mathjax.org/ http://www.mathjax.org/) is really excellent, has thorough support for many of the TeX-isms which you may ever need, and is really simple to include by CDN. I suppose that the competition here is really [mimeTeX](http://www.forkosh.com/mimetex.html http://www.forkosh.com/mimetex.html), since they both operate on the server-side, but MathJax is so very nice... The plotting is interesting. These are REALLY basic plots, but I do not know of any other web service out there which implements plotting functionality on the server side. (There seem to be a few defunct gnuplot services; I cannot find a working one.) There are many client-side libraries for charts, but none which concentrate on plotting functions. I'm glad to see it here, but I would like to see it improved as well.