[fab13n]

Real-time rendering is done pretty fast and nicely by whizzytex (sudo apt-get install whizzytex), if you don't need the collaborative features and are comfortable with emacs.

This being said, doing it in a web client sounds like no small technical achievement!

[JohnHammersley]

Thanks - whizzytex is a good package for real-time rendering. What we're trying to do with writelatex.com is help users get into LaTeX by removing some of the traditional barriers (needing to install, compile, etc), plus making it easy for existing users to work on the go and from any comp.

Hope you like the site! :-)