New mice often have lots of buttons. Some buttons are used by X and some are used by Applications:
- 1,2,3: Left, middle and right mouse button
- 4,5: Y axis mouse wheel
- 6,7: X axis mouse wheel
- 8,9: Foward and backward in browsers usually
But other buttons are not mapped to any function mostly.
My Mad Catz R.A.T.5 mouse has an additional wheel which sends button event 10,11. I mapped this to volume up and down using xbindkeys.
If you like this functions add this to ~/.xbindkeysrc:
#Vol+ "aumix -v +1" m:0x0 + b:10 (mouse)
#Vol- "aumix -v -1" m:0x0 + b:11 (mouse)
and start xbindkey on X11 session start. I use a line in ~/.xsession for this.