I've recently heard about http://ridejoy.com/ and think it was really brilliant, some years ago. But isn't the concept of paid and organized hitchhiking an old hat? Or is this totally new to the US market??
I've personally used services like that, often enough to tell that it's awesome. But anyway, this looks like a waste of ressources, when there are many other big players in the same field, no?
You'll find these services in Germany for the term "Mitfahrgelegenheit" => "to get a ride": https://encrypted.google.com/search?q=mitfahrgelegenheit&ie=utf-8&oe=utf-8&aq=t