I have tried many programs/applications to get perfect and easy output of math formulas. For me the best applications are LaTeX and Open Office formula editor.
Short guide to the LaTeX math
One latex editor online gives output as image http://www.equationsheet.com/textoimage.php
More like advanced editor online + wysiwg, you can export even as pdf files, if you have to make something fast and access it on google docs.
Yes you can even make math formulas even in terminal, can save output as image(.png). Why not use this to show off your formulas in web?