I have the same policy for comments on my blog as Lisa does on hers:
Comments and the “Living Room Doctrine.”
I consider my blog to be a virtual extension of my living space. As such, any comments that I would find threatening or offensive if said to me in person in my living room will be deleted. It’s fine to disagree with me (I allow that in my living room). Not fine is unbridled hostility, name calling, etc., either towards me or towards other commenters.