Our site uses PerlDesk. I was also evaluating TicketSmith but didn't find that full featured or nice looking
We are currently evaluating PHPManager as well as ModernBill if I can I would integrate my help desk system with my customer relation system, as when creating a new account I hate having to log into PerlDesk afterwards and create the same account for the user.
But maybe I can just write an auto script that will put the user information into PerlDesk when they signup hmmmmm....