In the event the traveler seeks layover privileges for purposes other than for transit through the USA, such as to visit friends or take part in sightseeing, the traveler is going to have to qualify for the sort of visa necessary for that goal. Since no passport is required anymore, you could be in a position to do the whole thing via e-mail too. If you try to apply for your tourist visa through an agency, you have to make sure that they are genuine.