CustomerFind (http://www.CustomerFind.com) is built around an idea: enter in keywords, then get notified about who is mentioning them on Facebook & Twitter. Then you get a neat way of replying to those people, in case you have a targeted solution to their problems. A small number of people pay for the software, perhaps because it is poorly marketed, or perhaps because there is a lot of competition in the social media monitoring space. Most people just use it for the email report functionality.
However, most people don't take full advantage of the powerful software I built. One entrepreneur was savvy enough to realize that I had something powerful on my hands, and now he's paying me handsomely to manage and grow his Facebook and Twitter profiles. I use CustomerFind to find people (targeted by geography and keywords) who might be interested in his services, and then one of my employees sends them a personalized direct message to start building the relationship. It's like SalesForce but for Social Media. I'm excited for what the future holds there...