No.16 Wiki

some says, Wikis are a great way of collaboratively developing a website, but they are not suitable for every web-based project. While some websites might benefit from the insights of the community, others function better under tighter control. If you are looking to develop content that requires input from people outside of the library, a wiki is a the ideal tool to solicit that content.

I found wikis are a very useful informal tool, i have used it to explain quite a few puzzles already, such as slang.

there was once i couldn't sit in front of TV for the last 20 minutes of the last episode of my favourite soaps, guess what, I got it all from Wiki the following week! other sites can't do such detailed description.

it sounds like a free forum for all. but the school teachers don't advise their pupils to go to wiki, as it is too informal, it may give u wrong info.