Domesticated Arcades is a website devoted to one do-it-yourselfer's penchant for making his own arcade game and custom PC cabinets. Check out the Completed Projects page for all the good stuff.
Incidentally, I found this page while googling 'Penny Arcade' for no particular reason, just to see what else (besides the excellent webcomic) could be found under that name. Domesticated Arcade's version of the Penny Arcade is a tabletop cabinet that uses a Namco TV gamestick and a television to keep overall costs down.
Not-Safe-For-Work Bonus Link: Here's the first item that comes up when you do an image search for Penny Arcade with Moderate SafeSearch on.