Open a Google Docs document, click on 'Insert' and select 'Equation' from the menu. You can type LaTeX code or use the drop-downs to select Greek letters, fractions, integrals, functions, summations and other operators.
Google converts the code to an image using an undocumented feature of the Google Chart API. If you export the document as a Microsoft Word file or in a different format, Google Docs will only include the corresponding images.
If you know a better online LaTeX editor, tell us about it in a comment.
{ Thanks, Bogdan. }
