One "BLister"'s impressions of becoming a 'regular' on the list: http://www.markkaren.com/markkaren/Bumplist/impressions.asp
Interesting to note the kind of community that emerges from it - as if the effort of having to constantly re-subscribe gives the regulars a common, uniting sense of having done some work to stay together. I guess there's a certain amount of gratitude and satisfaction if you know that the people reading your replies are there because they really really want to be there. I suspect there are some interesting aspects to the stats too - while only a certain number of people are subscribed at any one time, the mechanism allows a much greater community to actually stay up-to-date with a coherent majority of messages (i.e. so long as you see more posts than you don't). It'd be fascinating to see if the community changes according to the number of people allowed to be subscribed (and therefore the dependent number of "active" regulars)...
Still kicking about the ViralGroupBlog idea in my head, maybe 2005 is the year.
See also :