Much has changed in the two years since that post was published. Here is a 2012 remix featuring a mix of (mostly free) tools you can use on a daily basis.
The foundations for any social media marketing activity start with listening and in-depth research, ranging from influencer identification to campaign planning.
Best in class: SocialMention.com. As far as free options go, this is as solid as it gets.
As for more specific listening tools, each of the major social media platforms can be analyzed using a combination of specific tools including: