If you're not using Twitter actively yourself but want to track particular individuals, using an RSS feed is an easy way to integrate with your existing feed reader habits. Here's a neat trick to follow multiple people via RSS at once.
Every Twitter account has a built-in RSS feed (you can locate it in the right-hand column under the follower list). You can easily copy this manually and add it to your feed reader of choice, but if you want to do this with a lot of people, it can be a fairly fiddly process.
TwiTip outlines a simple method for adding multiple feeds, using Twitter's lists feature. Essentially, you use the Twitter Lists 2 RSS service to create an RSS URL for a list, and then add that to your reader. Hit the post for more details.