JStat: Statistical JavaScript Library

Wow, this looks really cool; I'm definitely going to play with this. Has anybody used it for anything yet? I'm wondering what the speed is like. Since it's pure javascript, I'd imagine it would be quite a bit slower than R. However the demo seems quite responsive, so maybe I'll be pleasantly surprised.

Direct link to the jStat site: http://www.jstat.org/

  jStat is a statistical library written in JavaScript that allows you
  to perform advanced statistical operations without the need of a
  dedicated statistical language (i.e. MATLAB or R).

jStat seems much more comprehensive stats-wise than other js libs. Lacking docs, the source is well organized and readable: https://github.com/jstat/jstat/tree/master/src

For a few stat functions more, check out Jason Davies' science.js, which was extracted from d3.js: https://github.com/jasondavies/science.js

For basic stats and math, MooTool's Array.Math has some nice functions: http://mootools.net/forge/p/array_math