I love the Player for going back and poring over my ride data. It'd be great to be able to smooth the graphs like in Garmin Graining Center. Specifically, being able to analyze how my average heart rate changed over the course of hours of riding would be very useful.
Even the maximum amount of smoothing in Garmin Graining Center is too little for my tastes though. I'd like to be able to smooth out data over 5+ minutes, not the 1 minute or so that Garmin Training Center seems to do. For hours of data that's still quite a lot of variability to look at the long term trends.