Another Great free tool by Google is Google Alerts, For those of you who still never used this tool - I think you will love it. with Google Alerts you can set up alerts, by choosing specific key words you are interested in, when ever a new post, web page, article, will be published in the net, holding the specific key words, you will get an alert to your email. this tool helps a lot in building quality back links, for example: you can track highly targeted web-pages or posts (related to your website key words), reply with comments and establish a good link exchange. Trust me, this tool is so simple and efficient, you will use it on a daily bases.