I like the sound control quite a bit, but I don't use Windows Media Player ever. While I appreciate the control having an option for Winamp (and iTunes, if you're into that sort of thing), my video player of choice is mpc-hc, and I'm sure some will also want vlc, or mplayer, or whatever. While you could try to add every player under the sun (and that'd be awesome!), having a button for the Windows play/pause, stop, prev track, and next track buttons--like when you push them on a keyboard with such functions--would be quite useful, as those tend to be configurable per-app and each user will know what to expect from them.
As a side-note--I'm not sure if this is a result of my keyboard's media controls being hidden behind a function key, but I could get the macro recorder to pick up the media keypresses either.
Edit: after poking around a bit more, maybe this should be under the Controls section--though I posted it here with the idea in mind that it'd be a part of the default Sound Control panel, so maybe a little of both.
