Just a random thought:
One of the niggling things that irritates me is that you now have to register at so many sites. Despite the similarity, registering at the Daly Kos does not register you at MyDD, or Oliver Willis' site, or Sean Paul's Agonist.
Blogger (belonging to one company) has a single login. That means no matter which blog you visit, you keep the same handle wherever you go. Maybe there ought to be a way to login at Kos and get the same handle reserved at affiliate blogs?
Now, the thing I'm envisioning is not so much a central login database, but more a central registration database. If I wanted to register at an affiliated blog, the handle would be checked against the clearinghouse to see if it was taken. If it is, then I could pull the contact info from that database for my new registration (after supplying the password).
It could, say, prevent people from registering MyDD under the handle of a Kossack for the purpose of smearing that Kossack. It would make the community of blogs more of a community by ensuring consistant identities.
But I doubt this will ever happen. This requires a lot of programmung fu and begs the question of who would own/control the ID clearinghouse...