MathML Torture Test
The following test contains sample TeX formulas from Knuth's TeX book and equivalent MathML representations. It compares the rendering by the XeTeX engine using the default Latin Modern Math font against the MathML rendering by your browser using the default math font, or an alternative OpenType MATH fonts. To get the best rendering, be sure to have appropriate mathematical fonts installed on your system and to use a browser with OpenType MATH support such as Gecko 31.0 (Firefox 31.0 / Thunderbird 31.0 / SeaMonkey 2.28) or higher. You may also try this test page for Mathematical OpenType Fonts which instead relies on Web fonts. Finally, you may want to check this table comparing how the tests are read by various screen readers for Mozilla browsers.
Link to test: MathML Torture Test demo