rome2rio is a website for travel options search. Enter a starting point and ending point and Rome2Rio shows flight, train, bus and ferry options to arrive there.
Do you want to see options to take a bus half way then catch a flight? Fly all the way? Fly to a major airport nearby and then catch a train? Rome2Rio will show you all these options, including helpful metrics like the frequency of each service. And it will compare prices so you can find a unique deal that combines ground and air transportation. Check out this example that shows travel options between Portland, Oregon and Eureka, California.
Prominent ground transportation carriers that show up in rome2rio results are Amtrak, Greyhound, Trailways, and Megabus. Many local and intercity bus and rail services are included using GTFS data. rome2rio includes more than 170 operators across the country.
The rome2rio blog post “North American buses and trains added to rome2rio” provides more information.
Update (20 November 2011): I asked rome2rio if all public GTFS is included. They said yes, and provided a bit more information about the ground-based transportation options that show up. This correspondence with rome2rio is at GetSatisfaction.