Maybe it's because I started my computing life as a Mac OS user but I still like having the ability to "roll up" windows like the old window shade action from the old days before OS X
as well as have the ability to minimize in the Windows fashion. That's what I love about linux: you can choose the best of both worlds.
To enable the roll-up / window shade action with the mouse wheel:
gconf-editor: navigate to /apps/gwd/, select the key mouse_wheel_action and change it to "shade".