Reid Hoffman may just be the guru of professional networking. Reid is the co-founder of LinkedIn, the web’s largest business-oriented social networking service. LinkedIn serves more than 259 million users in more than 200 countries and territories worldwide.Hoffman argues that your network is your career. Instead of focusing on a checklist of titles and skills that will get you your next job, he says you should invest your time in building relationships.The key is to think about how you can col...