Greetings again. In a definitely non-exhaustive survey, it appears that F, H, K, and L respond to the EDN0 NSID (RFC 5001) query.
1) Are there others that do so, at least on some of their hosts?
2) Are there rootops who do per-host identification in some other way?
3) Is this an appropriate topic for the RSSAC Caucus?
--Paul Hoffman