I've been running Wikidot.com for about 7 years now. It's a service that allows you to quickly set up a wiki, invite friends, edit pages and share stuff. It has about 1,300,000 registered users, hundreds of thousands of sites and is... quite large actually.
You can use Wikidot for free, but there are upgrades available - more space, more sites etc.
Starting today we accept Bitcoin. To give it a spin there is a 50% discount when upgrading account using Bitcoin. Yeah, it's Black Friday today :-)
Anyway, I am really glad we are finally joining the Bitcoin revolution!
If you need to set up a wiki, take a look! http://www.wikidot.com
Cheers,
michalf (Michal Frackowiak)