Just about done with my first (and probably last) mame cabinet.  Its based on RobotronNut's control panel layout and John P's Arcade Paradise 3 cabinet.  Kudos to both of those guys for answering my dumb noobie questions with patience.  And hats off to Scott at mamemarquees.com- just take a look at my side art and stuff.  Best money I spent without a doubt.  
I've posted a picture of the finished project. 
-I'm using a Sony 27" TV behind 
dark tinted plexiglass  clear glass and it works great.  
See note below.-The power on/off button is the right coin insert/reject button.  Press it once to turn everything on and press it again and it turns everything off.  I also have a key lock switch  to enable or disable the machine's power.  Useful for when the kids have spent too much time on the machine and need a "forced" break  

-The boot time on my PC is amazingly slow (1min 50 seconds until I reach the frontend screen) so I've got the TV displaying a Jpeg background that flashes 'Please wait' while the PC boots, and then just as the FE starts the TV switches inputs to display the game selection screen.  I guess you'd call it an unusual workaround to not see any windows screens 
  **Update**  Switched to a newer PC so the start up time is down to about 15 seconds.  I kept the jpeg screens anyway-I've got a volume control on the right front of the control panel and I find this very useful.
-I'm using 3DArcade for my frontend.  I'm surprised I don't see more people using it.
-Thats a pinball machine coin door in the front.  Just my preference to have a coin door thats wider than it is taller.  
-The cabinet is on wheels so I can move it to a different corner of the room depending on the activity level on the nearby ping-pong & pool table
-**Update**  Added 2 Act Lab light guns in July of 08.  The dark tinted plexi didn't allow the guns to work properly so switched to clear glass (which also required making a bezel to hide the TV).  The guns work really well now and I would highly recommend them.  I also made some simple holders for the guns using plastic tubing painted black (see photo).  -I'm using CPWizard to display control panel layout and other info when MAME is paused.  A really great app you should try if you already aren't using it:  
http://forum.arcadecontrols.com/index.php?topic=74091.0-You can't see it in the picture but there is a standard windows keyboard on a slide-out drawer below the control panel.  I use the keyboard more often than I expected since I'm always tinkering with settings.
Couldnt have pulled this off without all the good tips and info on this website.  A general thanks to the diehards who hang out here and help educate the masses.  Hope I can contribute something useful sometime.