Jabber server online.

Jabber is an open source messaging and presence platform. It has it's own messaging protocol, but also has the ability to interoperate and send messages to other messaging systems like ICQ, MSN, AOL, Yahoo!, and even IRC.

We've had a Jabber server running for some time here, but I've finally had the chance to get the Yahoo! transport set up so that using our server you can now talk to people using Yahoo! Messenger.

Jabber works very well behind firewalls, and even supports an HTTP tunneling mode to further that end.

Since it's a well published protocol, there are all kinds of client implementations, for Windows, Linux, and Mac.

Unfortunately, getting Jabber to speak to ICQ, and AOL is much more difficult to setup since their protocols have been changing lately, and AOL hasn't been taking well to "unauthorized" clients participating on their networks.