I have not seen many American driver's with a whole lot of talent to be honest. I wouldn't mind wringing the car out though
Front runners:
Possibly Kyle Busch (linked to a Toyota test)
Marco Andretti (give him a test)
Scott Speed (mediocre)
That Rossi character from the Formula BMW seriers looks promising.
Jenson Button appears to be on the market.
Other than that, the list looks short.
I say to start, Button to drive the car, Danica Patrick for some sponsorship $.