Wikipedia:Pidgin (software), the multi-protocol client tool based on libpurple written in C. The number one reason to use it is because it has such a pretty integration of OTR encryption, but there is also a reliability issue with OTR (see Talk:Encryption).
Pidgin and PSYC
Another reason is, it is pretty well architected for supporting multiple protocols. It shouldn't be hard to add another one. Since the client-side structure of things in XMPP and PSYC are so similar, I thought of taking the Jabber source code tree and adapting it to the new protocol.
Update: Marenz has started working on this.
The code to purplepsyc, a psyc plugin for purple is available at
Currently, the only thing it supports is connecting to saikound using gnutls and establishing a link to its identity (aka, subscribing to its _links channel). Nothing more.
libpurple gateway service for PSYC