Stephanie Leary

This plugin appends the author’s display name to posts and/or pages. There is an option to turn off the display on your own site, so the signature is visible only in feeds and crossposted content.

Post Signature

Appends the post author's display name to posts. Useful for multi-author blogs that are crossposted elsewhere, such as LiveJournal or Facebook.

etspring

NEW: Supports built-in WordPress comments threading! [see notes 2 and 3]
Automatically synchronizes comments from Your LiveJournal blog with Your stand-alone WordPress-based blog.
All imported comments are associated with Your blog entries, crossposted to LiveJournal, and shown along with comments, written in You blog.
You can choose how often do the synchronization.
Synchronization does not slow down loading of Your pages, everything is done in background.
Note 1: This plugin has to be used together with LJXP (LiveJournal CrossPoster) plugin. Support of JournalPress and other crossposters will come in future versions (please feel free to post feature requests at the plugin homepage).
Note 2: Threading depth is limited by WordPress settings (<code>Settings - Discussion</code>).
Note 3: You should consider removing <code>Reply</code> link for imported comments, because they are not really a part of WordPress :).

LJ comments import: reloaded

Automatically synchronizes comments from Your LiveJournal blog with Your stand-alone Wordpress-based blog.

Post Signature vs LJ comments import: reloaded