Allow users to help themselves. Aside of importing tickets from email, since version 1.2 WPHelpDesk allows to create public forums, where customers and support agents can interact with each other. This one feature will allow you to build community around your product or service and free some agents time.
You can control who can access this pages and build private or public support ticket section.
Both Agents and Customers can browse and reply to tickets in the frontend making it easy to keep track of conversation.
WPHD is bundled with ticket submission form which you can put on any page on your site. This form allows file uploads and is extendable using Custom Fields.