A list of Java instant messaging client libraries. Not intended to be exhaustive, just some I've come across while Googling.
- Joust -- low level OSCAR api
- jaimlib -- supports TOC protocol
- jaimbot -- Java AIM bot, includes a library
- SimpleAIM -- console AIM client
- JMSN -- MSN messenger clone, not actually a library, but there's likely to be stuff to reuse
- MSNj -- another MSN library, looks quite old