This Christmas I got a Bose SoundDock for "Team Sutton", and I have to say, it's the best $300 I've spent since getting the iPod from my mom last Christmas. In all seriousness: It's fucking amazing. The sound that comes out of that thing is better than my headphones (either Shure E2c earbuds or my Grado SR-60 over-ear headset -- both of which are supposed to be on the low end of what would be considered the "audiophile" range...). You can hear much more detail than I've ever heard from an MP3.
Not only is sound quality good, the quantity (volume) is fantastic, as well. When I plug my iPod into my stereo via a Y-cable, I end up turning the iPod's volume to max and I still have to crank the volume on my receiver. Not so with the SoundDock. Volume and clarity are simply off the charts.
Even though I have never heard any of the competitors, I just can't imagine any of them being this otherwordly in their goodness. I can't recommend the SoundDock highly enough.
Also, if you have an iPod and haven't sorted out your in-car options, I currently use, enjoy, and recommend the Monster iCarPlay for automotive listening with simultaneous charging joy, though the new iTrip Auto looks very interesting.
The only shame in all of this, of course is the amount of money a little gizmo like an iPod can make you burn... Ah, well, such is life, eh? ;)