LiveJournal supports the Atom API.
Atom API URI:
(Formerly, the Atom API URI was
http://www.lj-23-m.bulyon.local/interface/atomapi/username/feed. This, old, way
was redundant: after authentication, the username is already known, and is not needed in the URI.)
Atom API feed discovery URI:
FIXME: Currently this section is a placemarker. Needs expanding: extent of support; does it work with lj tags like the Blogger API support does, etc.