On the contrary, chatting and blogging are generally fobidden on wikis. Discussions are only encouraged when it pertains to the betterment of the site and it's specific articles. The idea is solely to collaboratively create an encyclopedic reference sourse for a specific topic.
Wikis are designed to be simple to use, in order enable the maximum number of participants. I posted a couple of links above, but once again here are some excellent examples of wikis using the MediaWiki software:
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http://www.wikipedia.org - A massive encyclopedia of every topic. You've probably stumbled upon this at some point even if you didn't know it.
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http://www.memory-alpha.org - A Star Trek wiki, probably the largest fan-based wiki online.
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http://starwars.wikicities.com/wiki/Main_Page - A Star Wars wiki similar to the one above.
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http://doom.wikicities.com/wiki/Entryway - A wiki pertaining to all things related to the Doom series of video games.
Being a big fan of Dark Shadows, I naturally felt the format would lend itself nicely to our favorite soap opera as well. Until recently, I too had been unfamilar/uninterested in the concept, but upon further investigation, I've found the format fascinating and the syntax extremely simple.