IMPULS (Instant Messenger Personal User Log Storage) is a toolset which allows to retrieve, store and display messages from different IM instances in a central database.
Everybuddy Java (EBJava) is a messaging system written in Java. It consists of an applet and a server, and is used to log in to existing messaging services (AIM, ICQ, etc) through a unified interface. User settings are also stored on the server.
A simple yet useful tool for browsing instant messenger log files (like Trillian, ICQ or Gaim) and also HTML server log files.
It has some interesting search modes and provides functionality that most messengers don't.