I know musicmusic has already posted a few of them, but I would like some more - like volume control, track seek, ect. Can someone help?

Erm, I don't really know what you want to accomplish with WM_COMMAND messages, but I can tell you that's almost certainly the wrong way to do it.

I almost forgot about this topic (sorry for lang. mist.)
There are few reasons I would like to use windowmessages (eg. to store all hotkeys in one single app., working with "special" keys and also in games, and so on...)
please - what about track seeking, anyone?
Here are for volume control:

Mute = 117
Vol inc = 102
Vol dec = 103

by musicmusic:
play/pause = 107
PAUSE = 40044
STOP = 40010
PLAY = 40009
NEXT = 40011
SHUFFLE = 40014
REPEAT = 40015
REPEATONE = 40042
STOPAFTERCURRENT = 40045
FOLLOWCURSOR = 40047
ALWAYSONTOP = 40041
OPENFILE = 40049
ADDDIRECTORY = 40035
ADDFILES = 40037
ADDPLAYLIST = 40038
SEARCH = 40040

You might want to use them with HoeKey or something (I know i do).

Anyway, that was a really old post crusader...

I cant remember if i said then, but just grab Spy++ or Winspector Spy to find the codes if you really need them, its not hard. (I hardly deserve credit for those codes either)

Don't put too much faith in those codes. They are subject to change.