Very interesting news site I came across : http://www.allsides.com/
that sells itself as non partisan.
Obviously there's no such thing as total impartiality, so instead of publishing their own articles, they source all sorts of news from various outlets and sort them into different categories. Very interesting idea, surprised I haven't heard of it before.
Also has a scale here : http://www.allsides.com/about-bias
Some trends that stand out:
1) MSM leans slight left (this is well- known).
2) There are more 'far right' papers than 'far left' or 'lean right'. Something I disagree with, I think this is just relative, since MSM leads slightly left already, so 'news' outlets like Huffington post appear \ less extreme in comparison to the general trend.
Worth a look.