If behavior, attitude, aptitude and ambitions are what the employer is looking to unearth before hiring the candidate then there could be nothing better than contacting - the maid servant for candidate's gender sensitivity', the plumber for candidate's attitude towards junior colleague; the landlord for candidate's aptitude towards others' property; and the girl next door for checking on candidate's aspirations in life. Interestingly, each of these references are only a mobile call away 24x7. Good luck with fresh hiring! If these do not apply in your case, get back for a new reference checklist!
For senior level hiring, however, may I recommend ex-boss's wife and candidate's driver as perfect reference checks!