JSPWiki is an open source wiki engine that enables a simple content website which any user can add or edit pages. The system supports authentication and authorization optionaly. By default it uses files system to save its data, so the setup and configuration of it is extremely easy. Also it has templates and many other features.

I used JSPWiki in two companies as a repository to store all projects documentation, knowledge base, employee information, and common repository for resources. It proved to be easy and very successful. I encourage you t give it a try.

You can also see a comparison of wiki software to try and decide for yourself.