http://webdemo.visionobjects.com/equati ... le=default
Some examples I made earlier:
Time-dependent Schrödinger equation:

Gibbs-Boltzmann Entropy equation:

Shannon Entropy (information):

Uncertainty Principle:

That one isn't quite displaying properly. The 'h-bar over 2' at the end should display like this:

De Broglie Wave Equation:

Inverse Square Law:

Enjoy!