HESK is a free Help Desk Software written in PHP/MySQL. It allows webmaster to setup a ticket support system on their Web site. It has all the features the big and expensive help desks have, but it’s user-friendly, lightweight and free. HESK.com also offers a remotely hosted help desk for a small monthly fee.

Trellis Desk is a powerful and Free Online Help Desk Software for your business. It Improves your company’s service by allowing your customers to quickly and easily submit support tickets to your team.

Jutda Helpdesk is a Django-powered ticket tracking system for small enterprise, designed from the ground up to be easy to use. It’s an Open source HelpDesk / ticket tracking system.

Jutda Helpdesk is designed to be easy to use, as ticket tracking systems are only useful when everybody makes use of them. To ease the pain of implementing a new helpdesk management system, there is a series of documents prepared to cover issues such as installation, configuration, and getting started with the software, read them here.

OneOrZero provides an Open Souce Help Desk Software & Knowledge Base Software backed by a highly configurable and extensible Action & Information Management System which allows you to ‘build your own system’ on the fly.