Edit: I've updated the list with some of the ones mentioned.
I wasn't sure the best place to post this, so I hope this works.
I am looking at expanding the labels that I currently have in sets available, but I would really like to get a sense for what people would actually use.
Here is my starter list.
Coin x4
Credit x4
25c x4
P1 icon
p2 icon
p3 icon
p4 icon
Mouse Icon (buttons 1,2,3)
Power Icon
Arrows for button direction (4)
Info
Save
Load
Audio
Turbo
Exit
Esc
Emu
Lists
Play
Pause
Vol +/-
Reset
Start
Enter
Back
Select (squeezed a bit)
Admin
Letters A-F
Xbox Buttons (A,B,X,Y,LB,RB,...)
menu
Flip (x2)
Launch? for a pinball plunger
What I am looking for is other words or icons that would be commonly used. The word "Reset" is about the longest word that will fit easily on a button.