A while ago I was thinking of supercharging my Beat and picked up a supercharger off of ebay after some research.
It's a 500cc roots type blower and it's fairly compact. Driving it 1:1 off the crankshaft gives about 8-9 psi theoretical boost on a 660cc engine so it's reasonably sized (although I know the Subaru Vivio only used a 300cc charger). The model is an AMR500 and they're quite popular on the web if you google them; I'll try and get some pictures and information up at some point.
Not in a rush to sell, but could do with a bit more money plus I'd rather it went to something interesting than sit gathering dust.