Wonderful article from Lifehacker here:http://lifehacker.com/5854053/how-to-stop-caring-about-trolls-and-get-on-with-your-life
Added bonus: it includes the origin of SIWOTI!
It's incredibly tempting, but try to ignore them the best you can. Don't respond to them, not even to call them out as a troll, and they'll go away. Even a simple comment like "please stop" or "go away, troll" can bring attention to their comments.
Just because the internet has a lot of psychos doesn't mean it isn't full of awesome people, and time spent arguing with trolls is time that could have been spent having meaningful discussions with others.
It takes a bit of practice and conditioning, but the main goal is to just stop giving a crap about what other people think—especially those that have nothing useful to offer.
I expect to pass through this world but once;
any good thing therefore that I can do, or any kindness that I can show to any fellow creature, let me do it now;
let me not defer or neglect it, for I shall not pass this way again.
-- Stephan Grellet