There is no shortage of TeX ↔ MathML conversion tools and solutions, one spectacularly prominent example is MathJaX (http://www.mathjax.org/) which can take TeX input and output MathML (for browsers supporting it) or do its own rendering into regular HTML.
Mathjax is pretty cool but it's also pretty slow if you have many formulas. While it's loading the page keeps rescrolling up and down because the document grows and shrinks. I started noticing the load after already ~30 formulas, quite big formulas though.
Also the distribution is a bit bulky, it consists of over 30000 files. You can remove many of them but then you also loose a big part of the compatibility. While speaking of compatibility, some formulas look kinda weird, but those are very few