Math in the World of HTML and JavaScript

At work I use a lot of JavaScript as our company (among other products) offers a map client that runs in browsers. As a side effect I frequently come across interesing JavaScript libraries. I find worth sharing. Here is an example of using JavaScript to display math formulas in a nicely formatted manner. To give an example, Einstein's famous formula will look like this:

$E=mc^2$

The library used for this display is MathJax. It should be sufficient for everything formula you reasonably expect on a website that does not dig deep into natural sciences or mathemtatics. In most cases it should even suffice for these fields of application. Here is a slightly odder example:

$U^{ik} = \frac{c_g^2}{4\pi G} = \left(-g^{im} \Phi_{mr}\Phi^{rk} + \frac{1}{4} g^{ik}\Phi_{rm}\Phi^{mr} \right), \quad -\nabla_\beta U^{\alpha\beta} = \Phi_k^\alpha J^k$

Well, maybe we better say it should be sufficient for almost any application ;-)