Подскажите тикет-систему

www.trac.edgewall.org
- не на php (python);
- GPL
- БД по умолчанию sqlite, но можно и в MySQL и в PostgreSQL

Если php не критично - самое то.

redmine.org

- не на python (ror)

rt

Не на php (perl)

Буду оригинален: Mantis (PHP, MySQL, GPL).

bugs genie

К сожалению на PHP

otrs

Description: Open Ticket Request System
 OTRS is an Open source Ticket Request System (also well known as
 trouble ticket system) with many features to manage customer telephone
 calls and e-mails. The system is built to allow your support, sales,
 pre-sales, billing, internal IT, helpdesk, etc. department to react
 quickly to inbound inquiries.

flyspray.

Bugzilla. На Perl, правда.

+1