Issue Tracker webapp designed by Ka Ping Yee. Now run by Richard Jones
http://web.lfw.org/ping/roundup.html
http://roundup.sourceforge.net/ includes a Zo Pe interface.
seems active (as of May'2008)
Possible piece of a Collaboration Ware suite, in combination with a Wi Ki.
On aspect widely lauded is the use of the Nosy List concept to combine the benefits of and EMail list and generic ad-hoc threading.
Has its own Hyper Db Data Store which can be used on its own.