This addon changes the following action bar labels, making them shorter and easier to read.
Alt is changed from "a-" to "A"
Numpad = N
Ctrl = C
Shift = S
Middle Mouse = M3
Mouse Wheel Down = DWN
Mouse Wheel Up = UP
Home = Hm
Insert = Ins
Page Down = PD
Page Up = PU
Space Bar = SpB
Mouse Button = M
All credit goes to Ketho on blizzard forums.