Just made a plugin for helping with user / authors.
http://geothings.net/osm/usertools.jar

plugin adds a new menu item to the top bar.
Select map data, show the author panel (alt-a), select a user from that panel.
Using the menu, click to open browser to open that user's profile page, for easy messaging, looking at traces etc
Using the menu, click to replace the map selection with all the selected user's map data.

todo:
Make it a right click menu for author table
Add a show user panel button
list all users in data

suggestions welcome.

source:
http://geothings.net/osm/usertools.tar.gz