Wikis, sites that can be collaboratively edited, are among the most popular tools for groups working together online. We've rounded up 30 of the best sites and resources - most of them free or low priced.
PBwiki - create your personal wiki in less than 30 seconds with this easy online service. Special solutions for educational, business and personal use.
OttoWiki - build up your personal wiki to track projects or collaborate on documents online.
WikiSpaces - create simple web pages that groups, friends, and families can edit together.
WetPaint - build up public and private wikis and join one of the largest wiki communities.
ServerSideWiki - create a web-hosted wiki specifically designed for extremely fast load times.
StikiPad - a hosted wiki solution that gives you an easy way to organize your information and share it with others.
Netcipia - create free private wikis and blogs and invite your coworkers, familiy and friends.
Ziwiki - build up a free wiki site and collaborate with a large community of users.
Near-Time - create and customize collaborative wikis for your business, customers and friends.
LittleWiki - set up free public and private wiki pages that anyone can edit.
TiddlySpot - get your wiki with no installation required and make it private or public.
ProjectForum - create hosted wikis to share, discuss and review ideas collaboratively (self hosted version available too)
Socialtext - build up a wiki in a few seconds. Different plans available for enterprises and smaller groups.
WikiBios - create a wiki page and edit your own biography. You will become part of a large social network.
Wiki - create free wikispaces of up to 5 members each with 25MB storage.
Wikidot - free and professional wiki publishing, collaboration and communication solutions.
Zoho Wiki - create free hosted group wikis and edit them collaboratively.
Wik.is - create public or private wikis and easily integrate them with your existing website.
JotSpot - popular wiki creation service that is momentarily suspended after having been acquired by Google.
Wikia - a community of users that create, share and discover topics they are passionate about through wikis.
EditMe - wiki hosting service that helps non-technical users to quickly and easily build editable web sites.
Versionate - create collaborative spaces where you can share information and review it with other people.
Self-Hosted/Open Source Wikis
ProjectForum - software to create wikis to share, discuss and review ideas collaboratively (hosted version available too).
Kwiki - wiki software with over 200 plugins that let you customize the look of your wiki.
XWiki - open source wiki released under the LGPL license
Twiki - enterprise collaboration platform and knowledge management system based on wikis.
OpenWiki - software that lets you create workspaces that can be collaboratively edited by anyone or by selected users.
MediaWiki - free software wiki package originally written for Wikipedia. It's available for everyone to use.
Confluence - enterprise wiki software that makes it easy for your team to collaborate and share knowledge.
Wiki Search / Browsing Tools
Gollum - a fast and user friendly tool that lets you browse through Wikipedia.
Qwika - search articles in Wikipedia with this tool that bridges the language gaps.
Wikiseek - another interesting service that lets you search items within Wikipedia.
WikiWix - search engine specialized in searching content within Wikipedia. (via)