Ask HN: How do you organize and share information within your company?

We are looking for a place to put all the knowledge we share into one place. The idea would be that when someone asks you a questions you answer in this place and send them a link to your answer. With a culture of always checking this resource first we could save a lot of time on repeat answers.

We tried google sites (mostly because it was a simple proof of concept) but want something more robust. We are looking at using a wiki right now.

What tools are you currently using and what do you like or dislike about them?