I recently started using the mobile location application / game Foursquare. It allows you to share your location with friends and earn points and badges for how often you share. Foursquare also allows you to integrate with your Twitter account to announce when you've "checked in" at a location, earned a badge or earned the status of "mayor" at a particular location. I had thought this was all great fun until Mike Shaver popped up on my Twitter feed.
I wouldn't say that I have a lot of followers on Twitter. 200 people seems like a lot but I'm sure a great deal is SPAM related so when someone like Shaver un-follows it makes me pause to assess the situation.
Twitter can be great fun to let your followers know what you're up to, where you are, what your eat or what's bugging you. There comes a time, however when you have to give back to the community. This applies not only to Twitter but to all internet content. If you're not creating and sharing, you're not adding to the community.
Also for what it's worth, I occasionally update Foursquare but have yet to figure out the long term value proposition.