Recently I back to a tool I haven't used for a while. Alex King's Tasks Pro webserver application is one of the best out there. The user interface, via a web page, is better than many applications made for the desktop. It surpasses many desktop applications in terms of interface, works well with PHP iCalendar and therefore is simple to integrate with calendar programs.
One thing I didn't see made terribly clear in the documentation is you don't need to run cron on the same machine as the web server. Certainly there are advantages in not having problems caused by network communications, but there is no need to do so, an advantage if you don't control cron on the webserver but do on a remote machine.
Next I plan to add a service module to allow clients to submit their tickets through a web interface directly into my task manager.