Blogs for activist and nonprofit groups

Rebecca McKinnon's started a volunteer site to match bloggers and groups-she also has a very useful handout on why to blog--PDF here.
An excerpt:
ELEMENTS OF A GOOD BLOG:
--Message: You must know what message or messages you want to
communicate and why.
--A clear goal: Know what you want to accomplish with your blog. It may
evolve over time to accomplish things you hadn’t expected, but without
a clear focus at the beginning you won’t develop traffic because people
who visit the site will see it has no focus.
--An audience: This may just be your funders, your members, or the people
in your immediate community – or it may be a global community of
people who share concern for your issue. But you need to have some
idea who you are speaking to. (If your blog is public you’ll gain audience
from unexpected places, but you must at least start out knowing that you
have something to communicate to SOMEBODY who is interested in
hearing about it.)
--Commitment: You need at least one person in your organization who is
committed to updating the blog regularly with clear, interesting writing
and useful links. The material may be pre-existing, it may or may not be a
full-time job, but the blog will not succeed with out somebody’s
committed efforts.
More here.