Google Alerts is a free service provided by Google where you sign up to receive “alerts” via email every time a phrase or phrases are mentioned anywhere on the web. To manage the email flow you can ask to receive these alerts in the moment, daily or weekly.
At the minimum you should be alerted every time your business name, or other key phrases (like your name, key products, etc.) are mentioned. This allows you to immediately be aware of any mention in the media, on a blog or on another website. You can (and should) also get alerts on your key customers (and competitors) to get a better sense of what they are doing and how the market is responding.
You may need to tweak with phrases at first as common names may produce too many hits. But try it and let me know what you think.