There are two schools of thought when it comes to following people on Twitter:
1) If someone follows you, it's good etiquette to follow them back (good karma, if you will).
2) It's perfectly acceptable to just follow those people who interest you.
Now, like many people, I have more than one Twitter account. The first one I use to send tweets on business and media news. It's primarily a marketing tool and the people and organizations I follow are a reflection of my professional interests (e.g. news, social media, etc.). I almost consider it a rolodex of sorts; something that provides insight about my associations.
My second account is strictly personal. I follow close friends and family so we can stay connected. If my cousin follows me, of course I'm going to follow her back. I want to know what she and my Aunt Gertrude are up to these days.
Now, is it rude of me not to follow everyone back on my first Twitter feed? Some would say yes, some no. As with most forms of social media, for better or worse, there are no rules. However, if you're a believer in "Twitter Karma," there's now a new Flash application which will help you identify those folks who you follow, but who don't follow you back. Their term for it? Whacking.
I don't know about you, but "whacking" someone doesn't seem like good karma to me. However, maybe that's just because I don't want to get whacked...