I recently came across an article by Rory Cellan-Jones about a new technology from Jigsaw, a development group at Google focused on making people safer online through technology. At the time they'd just released the first alpha version of what they call The Perspective API. It's a machine learning tool that is designed to rate a string of text (i.e. a comment) and provide you with a Toxicity Score, a number representing how toxic the text is.
The system learns by seeing how thousands of online conversations have been moderated and then scores new comments by assessing how "toxic" they are and whether similar language had led other people to leave conversations. What it's doing is trying to improve the quality of debate and make sure people aren't put off from joining in.
As the project is still in its infancy it doesn't do much more than that. Still, we can use it!