Wiki Website

I am wanting a wesite to be developed similar to that of Wikipedia, where someone can add information to a topic header very easily, and I also want it anonymously for the person uploading the information. I would like a search function on the website that people could search for topics or any keywords that might have been posted by someone else. Pretty much a carbon copy of what you can do on wikipedia. If possible the ability to post pictures, like a profile picture of a person, or place would be fantastic. Please let me know what you come up with. Thanks.