Lighting will be needed for the marquee area of your cabinet and is usually provided by either a fluorescent strip light, or several incandescent bulbs.
Coin returns may also be lit if your cabinet features them.
It is also possible to light up the buttons on your control panel. Knievel has created a nice writeup on how to effectively light translucent leafswitch pushbuttons which can be found here. Work is also currently being done in this area with the LED-Wiz