The arcadecontrols.com website listed above has got tons of resources. Mine is in the projects there somewhere. I also sell custom vinyl stickers for the buttons if you need any of those. (In the buy/sell section of that webpage, or just contact me)
I am still in the process of building my cab, but I've got everything up and running. If you look here
http://www.blitzbasic.com/Community/posts.php?topic=80705#908465 you will see a picture of my early test control panel. I have since added a Spinner and 3 inch Happs trackball. I got an actual arcade cabinet for free last fall,... it was in nearly new condition. The guy had about 20 for me to choose between,... he was just gutting the electronics from them and trashing the cabinet, so it was a pretty good find. My next step is to design the control panel into the existing cabinet. In the mean time though, my temp CP will allow me to get everything working.
I bought all my stuff through
http://www.ultimarc.com/ except for the trackball and spinner. They sell a device called an i-pac that is a keyboard controller. It allows you to wire everything up with no mess and no soldering. I'd highly recommend it.
The trackball I picked up off the web used, and the spinner I got from
http://groovygamegear.com/Good luck, and have fun!