1) Twitter Search often gives more accurate and timely results than Google, especially for breaking news. This is a trend that will only increase. Remember, Twitter is real time, Google isn’t.
2) Get more readers for your blog by using TwitterFeed to automatically post the first 140 characters of blog entries (or anything with an RSS feed) to Twitter, with a tinyurl linking back. This absolutely builds traffic to your site.
3) Find new friends with similar interests with Mr. Tweet. I’ve used this to find cleantech news sources across the planet.
4) Get tech support. Comcast is on Twitter, actively answering questions and doing support. Lots of other companies are too.
5) Get feedback on how your company or products are viewed. More than a few major corporations are doing this now.