If you're already using a Mac, you might be interested in Sandvox from Karelia Software. It does a lot of what iWeb did with some other customizations possible. You'd still have to find hosting, thought.

TextMate is a great text editor and it has a pretty sophisticated templating & tab-trigger system. You could define your own tab-triggers to produce templates that you fill in with the equations. The bonus here is that you can define your own.

I use the templating system for writing code, but the same concepts would apply to using it for equations.