http://search.lbo-talk.org/search/feed
You can perform special searches for subset-feeds:
http://search.lbo-talk.org/search/feed?subject=kill http://search.lbo-talk.org/search/feed?author=Doug http://search.lbo-talk.org/search/feed?msg=Zizek
That last one looks in both Subject & Body like the SWISH-E search.
By default you get the last 100 articles in reverse date order. There's a slight delay in posting to the feed because I'm using the search index rather than the postings themselves, but that index gets built every 10 minutes, which should be far more often than your reader checks the feed. I'm not putting email addresses in the <author> tag, but I'd consider putting a mailto: URL pointing at the list if people actually used that kind of thing. You only get the first 500 or so characters of a post, and at least in my reader it's not as useful as clicking on the link and going to the archives directly ... feedback offlist about how to make this better is always appreciated.
Have fun and let me know if you encounter any problems.
/jordan