This is far from perfect and even farther from scientific. It was done in 8 days by some passionate amateur developers. It was however a lot of fun and very interesting.

You can read about it and the team in more detail on the repo page here:

https://github.com/kelmerp/headline_sentiment_rating

and see some slightly more technical slides here:

https://speakerdeck.com/luizneves77/sentimental-headlines

This was written in RoR, Postgres (Memcached), and javascript + D3.

I'm also the creator of:

onionornot.com reddesigned.com http://luiz-n.github.io/route-search/

and am interviewing for web dev (and data visualization) positions in the chicago area if you would like to reach out to me. @hey_luiz