Bugzilla will do this for you. Its ment for software delopment, but could be easily used to run a helpdesk.
http://bugzilla.mozilla.org/
There is a email interface to adding bugs.
As Bubs from
homestarrunner.com would say..."check it out check it out check it out check it out check it out check it out check it out check it out .."
I need sleep
