LED information

[PCC]

This is a great site if you are using LEDs on your MAME cabinet.  It rates several LEDs, and even has an LED calculator that gives you the part numbers for the correct limiting resistors.
http://www.rc-cam.com/led_info.htm

[Sasquatch!]

Cool link.  Thanks!

[jets]

Thanks very much for the link  

[PCC]

You're welcome, most of the information on that site applies to all LEDs.  However, instead of powering them with a battery, you might decide to use a common AC to DC power adapter, or simply take power from one of the PC's power supply connectors; they are usually color coded as follows:
Pin1: Yellow (+12V)
Pin2: Black (12V ground)
Pin3: Black (5V ground)
Pin4: Red (+5V).

The LEDs listed on this site should be used to light things up (like coin rejects, buttons, translucent joysticks, plexi...); they are probably too bright for indicator lights.

I might try to light the plexi on my control panel - something like this:
http://www.pcstats.com/articleview.cfm?articleid=1137&page=2

As the LED Calculator site points out, when using multiple LEDs in a series, you must add the forward voltage (Vf) voltages together when determining which limiting resistors to use.  Instead, I usually prefer to wire muliple LEDs in parallel.