In reply to Rob Exile Ward:
Where I used to work we had a mixture of licences per core (although VM servers were all based on the host server cores not the guess servers core, unless you were running OVM of course), per call licences, user licences (although that was every user that could possibly get to the login screen not ever use that could login), and AFSU from a product we brought in from a 3rd party. No idea how it was all charged, we were just asked to make up numbers each 1/4 on what was deployed where and how many calls we had received. I now have moved away from anything Oracle and licensing is much easer (apart from JBoss licensing which will only get worse now IBM are taking over RedHat).
Good luck on your endeavours