I have been using Linkedin.com for a year by now. Some of my teachers and friends recommended me to use Linkedin.com for making professional connections.
So I started using Linkedin, and really, in one year, it helped me in building Industrial connections and also I got an internship in a startup in Bengaluru called Health Graph.
This was only because of Linkedin that I could build some connections and present my CV to companies and get an Internship offer.
Not only the Internship, I had connections build with the people from companies like Siemens and TCS. Also they are ready to hire me as soon as I complete my graduation.
It is a very good website, which helps a lot in one's career.