We use it here to keep our name visible. We'll put things out on the Texans, Longhorns, etc, and those get retweeted often. I've had some success with putting Twitter only service or parts discounts also. Using it to talk about joint ventures with local businesses and charities also produces lots of action. It has been cold this week in Houston (40 or so in the morning), so weather alerts, and such, are popular items also.