Wii in Japan is getting a new Virtual Console in October, and it's a rare one. The NEC SuperGrafx, a beefed-up PC-Engine (TurboGrafx-16 here in the States), saw a whopping five games released for it before NEC cut its losses.
You can still get your hands on one via eBay or by scouring Tokyo's second-hand game market (we found this one, new-in-box, for about $250 at the Akihabara Super Potato). Thankfully, Wii owners won't have to embark on a treasure hunt for a SuperGrafx or its games, the first of which to appear on VC is the console's launch title, a superb port of Capcom's Daimakaimura (Ghouls n' Ghosts).
Nintendo hasn't announced when (or if) this rare treat will reach US Wiis, but, given the fact that we're already seeing NEC console imports on the Shop Channel, it should only be a matter of time.