I was about to suggest MediaWiki before I even opened the link ;-) Going in depth in their database schema and code might be a good idea, it's got a lot of rea

I was about to suggest MediaWiki before I even opened the link ;-) Going in depth in their database schema and code might be a good idea, it's got a lot of really cool optimizations (which makes sense, considering it powers a top 10 site on the internet).