just chiming in to say that Concrete could also get some pimpin' style with that center-only attachment by converting those pizza pans into spinners. Paint some designs on 'em and watch 'em spin. It would just take a skate bearing in the middle in a housing. Maybe a script that says "SAVE GAS" when they spin at a certain speed?
Seriously, though, great job. You got me back in the hunt for disc wheel covers or something custom for my '04 Scion xB. I could always drill and tap the wheels but there has to be some disc cover out there for my steel wheels.