So, Hamm's gamepad thread shows quite alot of us use some sort of programmable input so lets hear what some people do with it! Also could help one another by sharing hotkeys and such.

I don't currently map anything on my g15's macro keys
For my g5 I map a few things on a couple of different games.

tf2:
I map engiee's equipment turn to the mousewheel nudge button.
mouse2 gets mapped to pistol quickfire
Been planning to map a melee attack>lastweapon script to thumb button

Warcraft3 (DotA):
I use autohotkey to map mouse wheel up/down to different inventory slots
Then setpoint both wheel nudge buttons and thumb button also to different inventory slots.