WetPaint

WetPaint.com is a free hosted wiki (they call it "website") creation tool -- think Blogger for wikis.  Whoa!  From their FAQ: 

Wetpaint sites are "click-and-type" websites that are easy to start and even easier to expand, because you can invite anyone you like to add text, photos, links, and other content to your Wetpaint site. To add or edit content, all you need to do is click the EasyEdit button to activate an editing toolbar similar to what you'd see in programs like Microsoft Word. Then just start typing!

It takes about a minute or two to set up a site (you get to select from pre-set design templates).  WetPaint does place contextual ads on its websites though, so as always, "free" comes with a cost.  Here's a sample site called WikiCancer.  To me, the site design is a bit busy and poorly-organized, but that might just be my non-digital-native mindset at work ;)