The Mac Mini is highly underrated, btw. That may be neither here nor there, but it's an extremely versatile and relatively inexpensive solution to quite a few non-obvious use cases.
- DVR
- To do mega-project: car install as all-purpose media server/center (though I have read that there are kinks in this sort of setup, especially as concerns audio)
- Home security setup / server for video feed
I should disclose that I own more of these little buggers than is probably warranted or advisable.
Some of these links are practically ancient, but they're where I started, and they are good jumping-off points:
http://macdevcenter.com/pub/a/mac/2004/02/13/home_automation...
http://boingboing.net/2010/06/24/ipad-home-automation.html
Let's be honest: the reason I don't go as far on home automation as he does is a) I'm not really interested in being a power user of some of the home auto features he advocates; b) I am too lazy/occupied to write a custom UI that would theoretically be foolproof enough for guests...let alone myself first thing in the morning before coffee. :)
Dislaimer 2: Alan is very much a kitchen-sink approach kind of guy (as is evident in the pics of his rather ungainly and uber-comprehensive UI), whereas I am a minimalist.