More and more businesses are using Twitter as a tool to communicate with customers. Some areas where Twitter can be useful:
Public Relations: Your customers may already be twittering about you, either positively or negatively. By addressing and responding to their posts, you can both turn around irritated customers and encourage advocates.
Customer Service: As an alternative to your standard customer service channels, responding to customers' questions on Twitter can be inexpensive and direct.
Promotions and Contests: Posting contests and promotions is a great way to generate a following.
General Tips: Useful information on products, trends, tips and other useful posts can be another way to attract followers.
View and excellent beginner's guide on how to get started correctly with this useful tool.