exactly.. all you can.. until u run out of buttons
on my Formula Ex, I've got:
shifters, clutch, speed limit, handbrake, horn, look behind, F9, F10, look left/right, ":-)", "WTF???" (;-P), and then cycle command "Shift+P, Esc, Shift+P".. not sure if i forgot sth..
Logitech Profiler does a good job of mapping just about anything you want.. cycle commands are the best..
in short, if there were 8 more buttons, i'd probably find sth to map to all of them..