Directory: HelpDesk

PHP web-based project management framework that includes modules for companies, projects, tasks (with Gantt charts), forums, files, calendar, contacts, tickets/helpdesk, multi-language support, user/module permissions and themes

This is a program very similar to other expensive Live Support Chats, xHTML and CSS compliant and...
Free and GPL.
It has also a WinApp but that is neither free nor GPL (but not too expensive).

This web-based business application is a great tool for assigning and tracking issues and tasks during software development and any other projects that involve teams of two or more people.
In fact, in only 4 weeks after its release, Issue Manager was downloaded thousands of times and is currently used at hundreds of companies and corporations, small and large.

LBE Web Helpdesk is operated entirely through your web browser and is designed to be used by both your support staff and your customers.