Issue tracking is managed using flyspray. Some of our flyspray projects can be seen at:
Some of the projects are private and can not be viewed.
Flyspray has the following functionality:
Allows task tracking
email notification (cutomisable)
range of task descriptors available
task status querying
task categories, state, type etc al customisable
Allows online access
Allows users to register themselves, or to require an administrator to manage users and user groups.
Task history (changes can be compared)
open source (ie, cost is in time invested, but can be modified)
tasks can be linked to each other