I think these suggestions would require hardware changes:

1.) Better sound.

2.) DTS or other 5.1 capability! (I'm glad HDD sizes are going up)

3.) Now that you own Replay TV as well, integrate them! I have a Rio Receiver and a Replay TV plugged into the same amp. That's silly, the Replay TV has more than enough horsepower to do Rio Receiver like stuff as well. It should be obvious that both users are probably in the same demographic! Also I have 2 replay tvs, it'd be nice if they could share the network or store stuff on the server so I didn't have to waste time programming both of them.

4.) RioCar is WAY to expensive for me, but when I get one, have a wireless card in it so that when its parked next to the house it can as the RioReceiver server what music I have and download updates to the car automagically. Having to go through all the hassle of maintaining lists for both music environments seems too much of a hassle. (And then when I park RioCar next to the boat, the boat can pick up my music too. Of course since my boat is parked in the driveway it really doesn't need that, but eventually I want a bigger boat and it won't be that close to my house!)

5) Wireless in case I have to go weeding in the yard or clean the shed or play in the yard or something.

6) Cheaper :-)