If someone mentions your product online it's probably obvious to most of us here that you should respond and say something like "thanks for sharing" or "let me know if I can help". That's kind of the bare minimum.. But I think there's often a much bigger opportunity in these situations and thought I'd share a little story as an example.
A few days ago someone tweeted about my product in a thread discussing client-side frameworks.
Beautiful. Easiest marketing material ever. Quote tweet it, add a little attempt at humor, retweet it to my personal account. People started checking out Divjoy and it took all of 5 minutes for that to convert to a sale.
And then @needcaffeine, being the god damn genius that he is, had an idea.
Which a few minutes later led to...
That led to a decent up-tick in followers, traffic, and sales through the rest of the day. Not bad for a few minutes of silly Twitter banter right?
One side-effect is that the more you do this, the more people will feel inclined to talk about you online (lets face it, they want that sweet sweet retweet and you're going to give it to them).
I'm not trying to come off as a marketing genius. I'm definitely not. That's the point. You don't always need a well-thought-out marketing plan. Appreciate customers who are willing to mention your product online, engage with them, have fun, and see where it goes.