If any of you use MySpace or Facebook, then you will definitely enjoy using Twitter. Twitter is a social networking and micro-blogging service that allows it users to send and read others users' updates (otherwise known as tweets-limited to 140 characters). If you have used Facebook it's like changing or reading your friends "Status Updates". Within these "tweets" you can post links, websites and emails. The majority of people just post a quick short statement like a response to "What are you doing?". You can follow particular people or people can follow you with your updates.
This has become so large now that companies are beginning to use Twitter to update there own customers. As an example hotels, airlines and airports are joining the Twitter community too, to pitch services, update travel conditions and respond directly to individual needs of customers. For the average user, this is a great way to network with like minded people. Let's say your a "DJ". You can search other "DJ's" and choose to follow them. Other Dj's may recommend a particular equipment, while you read there tweets; or they may post a link to an archive of music samples. So you can see the possibilities here. They also have http://www.twitpic.com which is the same as twitter but just using pics.