https://news.ycombinator.com/rss + http://gwene.org/

EDIT: Though I suppose it would be cool if comments worked, too.

I want that for mail. I keep planning to write something that can connect to an IMAP server and present the contents via NNTP, but it is low enough on my list that I don't know if I'll ever do it.

I know that the effect can be achieved by running an NNTP server, and using a mail/news gateway, but that's a lot more complex. Most NNTP servers are meant for big multiuser situations, and that makes configuring them complex, and often requires a lot of supporting software. Massive overkill for someone who just wants to read their mail in their newsreader and get a good threaded message view with a good UI.