Here are mine:
1. Parent/Child tickets. Basically expanding on the idea of tasks... allow sub tickets that can be assigned to different agents or groups.
2. Ticket list page refresh - it's probably a server load issue... but even a 5 min refresh would be something.
3. Some way to prevent users (maybe agents too) from re-opening old tickets. Once it's closed it should stay closed.. or could add option to allow the supervisor agent level to re-open them.
4. Turn off ability to create new tickets from e-mails while retaining the ability to communicate about current tickets. We want people to use the portal or call. We've found that allowing e-mail to the help desk somehow becomes e-mailing the support staff directly, so we'd rather just say no new tickets via email... but we do still want replies to come in to update current tickets.
Hmm.. maybe allow exceptions by customer.. for example if some auto generated emails are used to create tickets.
5. Customer portal announcement area - where agents can post status messages for system outages, etc..

