As Wikipedia grew in popularity, becoming the eighth most visited site on the Web, many companies decided to purchase and build wikis internally to help enable better communication, knowledge sharing, collaboration and project management between employees.

There are several free Web 2.0 offerings which help users who are new to wikis get their feet wet without installing software on a computer. We take a look at a four of them here:

1. Wiki: Google Sites (part of Google Apps)

Where it came from: Google Sites was built upon Google's acquisition of Jotspot, one of the companies that realized early on wikis had a future as a technology for the workplace.

Getting started: Signing up merely requires a Gmail account. When you sign into Gmail, click on the "More" tab and then "Sites" and you're into the app. You will be prompted to "create site" and you'll be able to decide rather quickly how you want to arrange things as they give you a few templates to choose from. A good starting off point is the web page view.

Ups: Have as many users as you want, and you can make the site publicly accessible if you wanted to take it beyond the corporate walls. Very easy editing tool that looks largely like what you'd use in your e-mail program, or a basic word processor. Like all the wikis mentioned here, you don't need to know how to write software code.

It's easy to embed video, links and other forms of media. There is great version control (so that if you don't like changes that were made, you can revert to an earlier form). Easy admin controls that allow you to make someone an administrator (who has the ability to create and terminate sites), collaborators (who can work within sites), and viewers (who can merely look at what's being done but can't edit). The ability to draw from Google Gadgets (a collection of widgets offered for iGoogle, such as a map or a stock ticker) is also nice.

Downs: No real mobile app to speak of. No offline mode. Though there are no ads to look at now, that could change as Google reserves the right to put ads on its consumer apps. Only 100 MB of storage per site. Pretty stingy considering Google's big server farms we always hear about.

2. Wiki: Socialtext

Where it comes from: Since its founding in 2002, Socialtext has been in the business of bringing social software such as wikis to the enterprise. They don't make their money off ads, so the free version of Socialtext (up to 5 users) is more or less a way for them to show businesses it is worth their time and money to sign up for their enterprise version that supports more users and contains more features.