Well being an Apple nut, I had been eyeing using a Mac Mini for a while as the centerpiece, and when Apple released the new model with the HDMI I jumped all over it.
For storage I'm using a 4-bay Drobo with a 1TB drive in each slot. The redundancy and overhead is great because if a drive fails, you don't lose any data.
Drobo
For my software frontend I'm using Plex, which is a port of XBMC for Windows. It's great - automatically scrapes TV and Movie databases online based on your naming conventions for show seasons or movies, and automatically adds posters, synopses, etc. to the browser.
Plex
It works real well too - for you iPhone users, you can actually get an app (I'm using Hippo Remote) to control the Mini with your iPhone - mouse, keyboard, the whole nine. Makes it easy to control.
Browsing on it is pretty hard though. The 1080p with the HDMI makes everything tiny on your TV but I use screen sharing on my laptop to set stuff up.
There are cheaper alternatives out there though. I can tell Count already knows about this kind of stuff, talking about NAS's. Only problem you'll run into with the PS3 and XBox 360 is video formats.
