I use mine for ESPN3, YouTube playlists I have created, Netflix, home videos, a very, very nice Movie and TV Show library and my iTunes music on occasion.
I do have a couple of Mac desktops and additional storage drives upstairs that keep everything, but you can set things up a little at a time with different budgets. My son is using my old MacPro for school and games and I have storage on it for my movies and stuff.
Ohh... and if you have other Apple devices, today's WWDC keynote might be interesting to you.