Ranked in these QuestionsQuestion Ranking
Pro Free and open source
Pro Public servers
BitlBee can be used without installing via community-maintained public servers.
Pro Supports multiple protocols and networks
BitlBee supports: XMPP/Jabber, MSN Messenger, Yahoo! Messenger, AIM, ICQ, and Twitter.
While the help command is informative and includes examples, settting BitlBee up requires a considerable amount of technical knowledge.