XMPP client
software to connect with an XMPP server
Miranda IM
Free instant messenger for Microsoft Windows
Pidgin
graphical multi-protocol instant messaging client
Conversations
Android XMPP client
Psi
Instant messaging client
Mango
non-commercial software for handling medical images
Profanity
text mode instant messaging interface that supports the XMPP protocol; runs on Linux, OS X and Windows using Cygwin
Gabber
free and open-source instant messaging client