I joined Twitter back in September of 2007 as one of the early adopters, but even still I was member 8,845,922. Now there are hundreds of millions of users, with some saying we are approaching over 250 million active users before the end of the year. Twitter is truly mainstream. Don't have a twitter account? Get one! Twitter is great, but only if you are following people. If you are the only one on your feed, you are literally talking to yourself. While you will hear many talk about how many people follow them, it's really about how many people you follow and to a lesser extent how many people you share a bi-direction relationship. In other words you follow each other.
Not sure who to follow? Below are some of my lists. They are tech heavy, but there is a fair mix of actors, news people and politicians.