I had the pleasure of meeting the team from Jelli (http://www.jelli.com) a few weeks back. Jelli for those of you who don't know it already is 100% user controlled radio so what Pandora is doing for music is what Jelli is doing for radio - totally crowdsourced.
The site I have to admit is so easy to use it's addictive; within seconds of registering you are affecting the world of radio, as we know it - "rocketing" songs to the top and "bombing" songs to the bottom of the list.
Founder and CTO, Jateen Parekh explained to me how radio stations are basing their song selection on the listeners of Jelli and getting great results. In fact recently two radio stations have been completely taken over by Jelli progamming!
Radio stations both small and large are crediting Jelli with increasing their ratings. For example - 94.5 PST out of the Philadelphia area is reporting - increased ratings, increased impressions and best of all increased revenue for the WPST night show by 12X!
Jelli listeners have proved to be 100x more active then Pandora listeners and make 300 actions on average per month (actions are defined as Likes, Dislikes etc) which is easy to imagine since its so easy to use.
So I like to classify this ROI in Social Media as an approach that leverages the data of social media. Much like you are able to optimize your media spending based on social media data, or optimize your keywords selection based on what's trending in social media here is an example of serving up what your audience really wants to hear (in real time) and having it affecting market share and revenue. Now that's a real ROI in Social Media!