Mozilla has createdan extensive bug tracking system called Bugzilla. Bugzilla@Mozilla (BMO) tracks bugs for every Mozilla project, but specially Firefox and its components.  Any user can submit a bug, choose a severity, or set it as an enhancement bug (just a simple suggestion).  Other users, including Mozilla employees, can comment and do much more.

Bugzilla is capable of filing a bug for any Mozilla product, service, website, etc.  When you click the button to file a bug, you will be shown a list of common products.  You can then click "Other Projects" for a full list.