I actually just implemented Trac at the company I am with. They were in a similar state for their issue tracking (mouth, emails, sticky note, short bursts of development with potentially very long intervals between software releases). I did a little research and ended up with Trac
http://trac.edgewall.org/ It comes with a wiki, issue tracking, integrated source control (if you want it), easy searching/reports, plugins, SVN plugin, and it's open source. It is a web-based system so keep that in mind.
Installation was easy as well. You can set up yourself (perl, apache, mysql, etc.) Or you can use Bitnami to install a fresh instance
https://bitnami.com/stack/trac... there is plenty of documentation to get an instance installed and configured fairly easily. For non-techies the Bitnami installation is huge because "out of the box" it works fairly well. Configuring will take a little know how but once that is done it's smooth sailing.
We just released it to a wider audience of our customers and the feedback has been well received. It took a little time for me to setup but within a few days it was up and running behind SSL and authenticated to our active directory with LDAP. Anyone on our network can easily log in and the permissions are set up as a per project basis (each user is assigned to a project group that can view/edit wiki,tickets of their associated project group).
It has only been a short time since we released it so there still might be some growing pains but it so far has help us get away from change requests in word documents and email.
Funny enough, I was about to ask
/. the same question months ago before I landed on Trac. Hope this helps. Good luck!