For some time I've talked about setting up a CalDAV server in my home. River won't share her calendar on any service outside the home (including Calgoo) because of her concerns about how secure and private the info is. I respect that.
The really expensive solution is to buy a Mac Mini plus Leopard Server but we're already talking a couple of thousand dollars just for that. So that's out.
I'm now looking into either buying a very cheap diskless PC and running OSAF's Cosmo on it, or installing Cosmo on a PC I already have and just leaving that PC on all the time. I may actually try the latter first to see how it all works. Ultimately I want the CalDAV server to just run 24x7 so it would be great to get one without a hard disk spinning all the time.
This month there's a new release (1.1.0) of the Cosmo server. The installation instructions are not for novices. But for pure LAN-based, widely-interoperable calendar-sharing messing about, it looks like the best game in town, nowhere near as challenging as installing Kerio's mail server or other solutions which might be overkill.
Please let me know if you've tried Cosmo 1.1.0 and what you've experienced.