In the case of my mac mini, it's connected to my Pioneer AV receiver and is also my HTPC (rather than using an ATV) - it's enjoyable browsing on my 65" plasma.
I use the remote app on the watch to control my iTunes on the mini. (and, before anyone asks - the artwork is just a vague, distant coloured square in the background of the remote app - I wouldn't expect nor need it otherwise)
Oh...and I want Apple to do up the Activities app for the mac, so I can see nice graphs of my history on a decently sized screen (as opposed to iPhone).