In the case of National Equip. Rental Ltd. v. Szukhent  375 U.S. 311 (1964), the Szukhents (farmers) of Michigan, rented some farm equipment.  The small print of the contract said that the Szukhents appointed the wife of the VP of National Equipment as their agent in New York.  When things went wrong, Nat'l Equip sued them in New York, serving the wife of the VP.  This went up to the US Supreme Court on due process grounds.  The Supreme Court found that, as a matter of due process, there is nothing wrong with the farmers appointing a New York agent for the purpose of receiving service of process.  It is simple consent.  The important lesson of this case is that you can always consent to jurisdiction, no matter how much contact you have with that State.