There are a lot of Wii peripherals out there, but hardly any of them are impressive enough to incite levels of 'want' that would make us consider handing over our hard earned cash.
CTA Digital has an inflatable racing kart for the Wii that also supports Wii MotionPlus. Compatible with Mario Kart; Need for Speed: Pro Street; Need for Speed: Nitro; Need for Speed Undercover; Exite Truck and pretty much any other Wii racing game, the blow-up car sports a plastic steering wheel that serves as a dock for the Wiimote and is probably durable enough for us grown-ups.
The CTA website isn't specific on the size, but it does say the car can support up to 300 lbs so as long as you can squeeze into the seat (which looks pretty roomy), then you're good to go.
Joystiq reports that CTA is also using the peripheral's marketing to publicize Kids Are Heros, an organization that encourages community involvement among kids. CTA is even using Ricky Springer, who races real go-karts to raise money and awareness for Eosinophilic Gastrointestinal Disorder, as a spokesman.
Cheesy demo video below.