The jsMath package is an option that uses LaTeX markup and native fonts. Quoting from their webpage http://www.math.union.edu/~dpvc/jsMath/: The jsMath package provides a method of including mathematics in HTML pages that works across multiple browsers under Windows, Macintosh OS X, Linux and other flavors of unix. It overcomes a number of the shortcomings of the … Read more
The other answers are out-of-date. As of 2012, beautiful math is easy to write and render. The technology is called MathJax. You can see it in quiet action on MathOverflow and hundreds of math blogs. MathJax is an open source JavaScript display engine for mathematics that works in all modern browsers. No more setup for … Read more
After some digging, I found some somewhat official recommendations. Unfortunately, most are not functional at this point in time. Both the browsers and the screen readers have a lot of to implement before Math and SVG can be considered accessible, but things are starting to look up. Disclaimer: the below recommendations are what I have … Read more