Multiple reasons and people actually. Probably more on that later.
But for now this article by Abraham Piper at the DG blog persuaded me the most.
http://www.desiringgod.org/Blog/1156_6_reasons_pastors_should_blog/
Now for grace to execute the stewardship well.
curtheffelfinger.com 
John Piper strikes again! What an influence this man has. Let's rejoice in God's goodness for allowing us to have such spiritual mentors at this late hour…
Now I've got two members. This thing is growing at breakneck speed. Thanks, brother.
I'm definitely very happy about being a 'member.' Anything of eternal spiritual value involving you is something I want to be part of. While on the subject of eternal spiritual realities, here's a quote from Robert Murray M'Cheyne to fan the flames, “What a man is alone on his knees before God, that he is, and no more.”