If you implement following functionality I know some customers who really appreciate that because no other tool allows to do it:

We need your nutshell functionality with a small add-on. It would be nice if we could get email alerts (like you already provide) that gives us an overview about who, where and when special keywords (we define regulary) are used in a tweet, post or blog. But not overall but in between my existing network. I know this kind of search is common but it is never restricted to my contacts. And exactly that would be a great advantage for every sales people!

The mail should tell us: today these people posted, tweeted about your keywords in between your existing contacts.