Intranet portal for the project

Trac and MediaWiki will be my top pick, depending on whether you want to integrate a ticket. Also keep in mind that MediaWiki has a robust plugin ecosystem, so anything you would like to add above and outside the wiki and discussion functionality may well be available.

Redmine is another good choice - I don't like it as well as Trac, but it's much easier to set up on a shared host where I keep my project management tools.