Now that the day job is looking like it’s going to be more and more SOA oriented, in the WS-* sense, my interest in less complex things that can play in that space is getting piqued. It’s been clear for a while that XMPP is going to be one of those things — there are a lot of things you can do on a foundation of durable messaging and presence.
There’s an extension to the protocol to support the Pub/Sub model which allows, among other things, pushing updates out to an XMPP server instead of requiring clients to poll a feed — with built in support for authentication and SSL. More experimental work concerns “shared editing” of documents.
Set up a private server, and run clients on the systems you administer. You can query, monitor,and even run commands on the them; support for presence lets you see which of them are currently online. Take a look at the list of Extensions to XMPP already available, or in progress.