You can create RSS statements for any source that generates fresh content from time to time. One would assume there would be a vast array of tools for converting events in one system into a blog plus and RSS statement. Surprisingly I'm not aware of lots of these.
MailManRSSFeeds -- Mailman Archives -> RSS http://taint.org/mmrss/
NntpRss -- RSS->NNTP
CheeseGrater -- HTML->RSS http://www.jwz.org/cheesegrater/
BlogLet -- RSS->Mail http://www.bloglet.com/