Edward Tufte recommended this cool site to collaboratively write scientific papers or technical presentations in LaTeX. Amazingly there's no software to download, it's all in the cloud. The WYSIWYG viewer in the browser is worth checking out. You can get an extra 50 MB for your free account using this invitation link: https://www.writelatex.com/signup... Every document you create has a secret link. Just send it to your co-authors, and they can review, comment and edit. Outputs PDF, of course. - Adriano