The list of open source helpdesk software we can supply or host, install, configure, and support (at the time of writing) is as follows :-

Title	Version	Description	Rating
FAQMasterFlex	1.0	This is a database-driven application for creating and maintaining Frequently Asked Questions.
Help Center Live	2.1.7	A problem reporting and help desk application.
PHP Support Tickets	2.2  2.0	A feature-rich PHP helpdesk.
phpMyFAQ	2.0.13	phpMyFAQ is an open source FAQ system using PHP.

If there is a title that is missing off this list we might be able to install it for you.