how to light up a button?

hi! very self-explanatory title, not an RGB led, just a normal 5mm one, and a common momentary switch. i'd like to have a very dense array of buttons, so it is important to have the led just underneath or above the button.
maybe similar kinds of buttons are already sold, in this case i'd like to know which supplier makes them.

thanks in advance for the help!

In this project I Incorporated an LED with switch to do just what you want. Light the LED when the switch makes contact.

I used a reed switch but it can be any sort of push button:-
http://www.thebox.myzen.co.uk/Hardware/Pendulum.html

oh, i'm sorry, i forgot to say that the led has to be completely independent from the button.. the just have to be in the same position, in order to get some kind of "visual feedback" to the button..

Grumpy_Mike, your blog is in my arduino favorites top 10 :wink:

This looks like what you want: Button Pad 2x2 - LED Compatible - COM-07836 - SparkFun Electronics

thanks for the advice!
i've already seen in spakfun, the matter is that in order to use them i have to buy the rubber buttons and the breakout board that actually store the contacts, making the buttons useless alone. so i would get 16 buttons for 1.25 each.

Button Pad 4x4 - LED Compatible - COM-07835 - SparkFun Electronics 9.95$
http://www.sparkfun.com/products/8033 9.95$

total = 19.90$ (plus shipping)

not a big deal considering i need 30 of them.. only them cost more than all the other things..