How do I install a wiki on a CentOS 6 vps?

Not sure where to start the choices are many and to be honest I feel a bit overwhelmed. I need something that will let me create pages, manage users, and handle youtube videos and images. I am fairly competent on the command line and was looking for some advice or opinions. This is my first time playing around with CentOS and I have to say I really like it. Also can someone explain what the differences are between CentOS 5 and CentOS 6?

edit: Thanks for the suggestions. I will post an update when I get one installed and working :)