Windows Live Writer is a blog manager. It lets you sign into multiple blog accounts much like Mail would let you sign into multiple email accounts. From there, you can create new posts, update old posts, etc, as if you were logged into whatever blogging service you already use.
Even though I only regularly update this blog, I can see how this can be really useful. I may even update more often… or create other blogs!.
It does the same type of work that I think Adobe Contribute does, except this is free. So, I can’t complain about the price.