Comment another OTRS vote (Score 0) 321
OTRS (can integrate to any auth' source and or any DB)
GLPI (haven't dug in yet but looks nice)
I wonder how we all can integrate XMPP in to OTRS? Sounds interesting & do-able but then again why not just use email or HTTP.
I am laughing at all the responses who call both the poster & his users morons for the quantity of questions they have. Sounds like they need a Wiki (to use as a FAQ) & to point the users to before submitting their ticket.