Referees are sometimes required on CVs, but even if they’re not they will be needed at some stage. Always ask their permission first. Referees who work in the same industry as the organisation you’re applying to are the best, and the better known they are, the more useful. School-leavers and new graduates looking for a first job can call on teachers or tutors to vouch for them, or a responsible leader of any clubs or organisations they have been a member of.
(On a related note, follow the link to find out what your rights and options are if your request for a reference is turned down by a previous employer.)