Hopefully it's not considered bad form to respond to a topic that's a few months old.
I've been using my RPi to run my media centre. I love that something that runs from a phone charger can replace the full on desktop I used to use - it even decodes X264 natively!
I'm using OpenELEC and the PM3.HD skin. The skin doesn't perform quite as well as the defaults but it's the one I've used the most and I'm comfortable with it so I'll take the hit.