Owning the power of the press is good - blogs are also strong promotional tools.
It challenges me to act the way I want to act
It is cool.                                                                                     It increases communication.
It is a gateway to other Web2.0 techniques.
It increased personal profile.
It is a good discipline - discipline in one area tends to create it in other areas.
It keeps me aware and crisp. 
Sometimes it inspires someone.
It helps people to know me - people tend to help those they know.
It is a great way to keep in touch with many people.