There's using Twitter as a resource, and then there's wasting time. If you want to use it wisely, use Twitter as a research aid. Twitter provides you with a readymade audience to ask questions. You can plug keywords into Twitter's search function to find information on a topic you're researching and see what others are saying about it.
If you're a blogger who wants to drive traffic to your site, or if you're running a business, you can use Twitter as a marketing tool to build name recognition. It's not even necessary to have a long list of followers to have success. When you reply to someone else's tweet, your name and avatar will show up as well. So if you add interesting, relevant comments to someone else's tweets, you bring attention to your name and you might even collect more followers.
Whatever your business or interest, look for what people are saying about it on Twitter by using a hash mark (#) before the search term. If you're providing a link to a Web site or blog, run it through a site like tinyurl.com to conserve space.