Disclosing personal information?

How much personal information do you have to disclose to a potential landlord these days? Does a landlord really need your SSN, checking/saving account #, disclosure of bills (student loads, auto loan and insurance, etc.). I can understand a credit score check but everything else seems to be over kill and an invasion of privacy. Plus, I cannot find any law that dictates that you HAVE to disclose any of this stuff to any private merchant, i.e. landlord.