I'm checking out a new project called Gale. At MIT, we used this messaging system called Zephyr. Zephyr was cool because it was ubiquitous on campus. If you were looking for someone, there was always a good chance of fiding them online, or someone who knew where they are. You could subscribe and send to different categories of messages, some for given student groups, others for generic help (in any area) and discussion, others more specific, like one for NetBSD users. It's sort of like email and mailing lists, but real-time, a lot more dynamic, and less "formal" (if that makes sense). It was also tied into system services, so when the printer is done with your job, or your fileserver is going down for maintenance, you'd get a message about it.
Anyway, I still log in to MIT to use zephyr every day, and I wish I could do something similar with a broader group; say all of my friends, or the Darwin community, etc. I've looked at AIM and ICQ, but they stink at the group dynamic. They are OK for messaging specific people, but not for group discussions.
Unfortunately, I think Zephyr is pretty much dead. I mean MIT will probably use it for the foreseeable future because they've always used it, but the last Zephyr release (2.0.4) was in 1996. There are all sort of features that Zephyr could have, and there are patches around for some of them, but it really seems like MIT isn't doing anything with Zephyr any more, so I'm giving up on it. The need for a kerberos realm to authenticate message is also a bit of a pain. I do use kerberos, but it's not trivial to deploy and manage a realm, and it's not really the right thing for an open user base such as the Darwin community.
Gale is a new thing which aims to replace Zephyr (and has at Caltech). Not I hate to plug Caltech over MIT, given my academic roots, but there you have it. Gale does what zephyr does plus it fixes a bunch of things up, claims to be faster, leaner, and meaner, and looks like a good shot at picking up where zephyr left off.
The one drag I've noticed so far is that it's under the GPL instead of a free license, which tends to be a nuissance at best; but it's a common faux-pas, and one can't expect perfection.
I've also started porting OpenSSH to Darwin, since ssh is an important tool, and we all know the ssh1/ssh2 license fiasco. I was working with the OpenBSD code, but a couple of folks pointed out that now there is a cross-platform version that uses autoconf and so on, so I'm now using that. That's coming along more nicely, but it seems Darwin lacks /dev/random, though, so we need to fix that in order to make the OpenSSH build happy.