Wikipedia has had an enormous impact on the ideas people have about an encyclopedia. It has created a whole new concept in collaboration all around the world. Users in many countries now can join the effort in creating knowledge and working together in a global wide project. Besides, it has created a new type of job (although not remunerated), the wikipedian.
Wikipedia popularized the concept of a wiki, a concept made possible by the MediaWiki software. After the growth of Wikipedia there has been a number of new websites based on wiki software, related and founded by the same foundation and some independent projects, as MediaWiki software is GPL. Examples are wikia.com, wikiversity.org, wikinews.org, etc. Also, many people in the world can contribute due to the fact that wiki projects are usually multilingual.