1. Twitter (www.twitter.com)

An immensely popular microblogging site, Twitter allows you to build upon your social network by "Following" people's updates. An update must be 140 characters or less so that it can be sent via SMS text message to a user's phone. Twitter is a great tool for: - expanding your network of personal and professional contacts, - staying up-to-date with industry news and knowledge (especially marketing & social media), - promoting your product, blog, website, or yourself.