What is a good open source issue tracking system for non-developers?
Solution 1:
Non Software: I At a previous place of work that we use to work at, we used OTRS (http://otrs.org/) It is for a non-development environment (doesn't have fixed in build, found in build etc..). We set it up to authenticate against our windows AD.
What I like about OTRS is that it can integrate into Email AND Web. So users can email in a problem, it will open a ticket, and then you can log into a web interface and answer them back to their email. If the user wants to use a web interface 1/2 way through, they can... and everything that they emailed back and forth is stored as notes. Its all seamless to you and the user.
You can also have 'canned-responses' so you can email a user or put a note in a ticket without typing everything again.
OTRS also has a FAQ section, where you can put a 'how-to' section. It also can reg-ex certain words and put them automatically into different queues.
Software: for Software bug tracking, (the place that I am now) we use Mantis BT. I would say its very easy to use and setup, we authenticate against an openldap server.
Solution 2:
Wikipedia has a Comparison of issue tracking systems