I have written before that I have a large movie collection ripped to a 16TB raid. In the past I have used SageTV to stream, but Sage was bought out by Google almost a year ago and has gone totally dark since then. So I switched to XBMC, which given I am not messing around with PC-based DVR, actually turns out to be a better solution from a software standpoint. I will post on my progress next week. The problem is getting a low cost streaming box to run it, like Sage had with the HD200 and HD300.
Here is the hottest product in the geeky build-your-own end of home theater, the Raspberry Pi. A tiny computer board that apparently will run XBMC (I presume the Linux version) and stream at a full 1080P and costs about $35. Right now, XBMC users are using either dedicated PC's or hacked AppleTV boxes. I have one of each on the work bench -- the dedicated PC is expensive and the AppleTV box based on the old ATV2 won't run 1080p. The new ATV3 will run 1080p but no one has apparently rooted that yet, and besides it is still a lot more than $35. So I am on the waiting list for my Pi.