I've expanded the list of Other Blogrolls on the sidebar to include Carnivals. These are summaries or updates of some broad subject done regularly, but hosted by a different blog each time. The two I've added are the Carnival of Space, done every week, and the Philosophers' Carnival done every three weeks. The links take you to the home page which links to each of the individual hosts. I'll probably add more as time goes by.
Update: Only a few minutes later and I've already added the Patristics Carnival.