You can use the popular Twitter site even if you don't have an account. Without an account you can still see messages posted publicly by others, and search for hashtags and specific news.
Learn how to use Twitter lists to organize your Twitter home page. You can group together people you follow by category and view only that list. You can also see which lists others have created and follow a list that fits a topic you are interested in.
Learn how to build a following on Twitter using a selection of techniques to create an audience that is interested in what you have to say
MacMost launches a new Mac Users Guide to Twitter section. In this video, if you are new to Twitter, find out how to find interesting people to follow to make your Twitter experience better.
Gary Rosenzweig takes a look at Twitter, the free service that lets you and your friends keep track of each other. Follow Gary on twitter by going to http://twitter.com/GaryRosenzweig/