I doubt Ohio will be the last to be called, unless it's within 1%. The votes get counted more quickly than in other states. Factoring in the time of poll closing/speed of results...
Alaska (since it's the last to close, and counts its results slowly)
Arizona
Georgia
Iowa
NE-02
Despite the time difference, Alaska usually gets called for the GOP fairly quickly. Is there any reason to think it will be close this year?
I'm not necessarily saying it will be close, just that there might not even be five other states left to call by the time it closes. It was called for Romney right away, but it was still one of the last states to be called in 2012.