I visited three Wiki sites: Wiktionary, Greetings from the World, and the Holocaust Wiki Project.
Wiktionary: Like Wikipedia, but a dictionary. It appeared rather easy, but I did find shortcomings. I wouldn't trade in www.m-w.com or www.dictionary.com in for Wiktionary. Why, you ask? Well, Wiktionary just gives the definition and an example of the word used in a sentence. I want more than that; I want root words, synonyms, antonyms, etc. So, I don't foresee myself using Wiktionary as a dictionary. However, I do see a potential for my students to create their own Wiki Dictionary during a lit class. For example, we are reading Jane Eyre in British Literature and the vocabulary is fairly rich. It would be good practice to have the students enter in vocabulary words into a common dictionary. So, at least I took away one idea from Wiktionary.
Greetings from the World and the Holocaust Wiki Project: both make me want to be a history teacher! Well, I technically am a history teacher, but I don't teach history. What a wonderful concept. I think that the Greetings from the World wiki could be set up differently to make it more approachable. I see that they have broken down geographical areas on the side, but the information seems to crowded and overbearing for me to want to navigate and read. Perhaps they are growing faster than anticipated? The Holocaust wiki is much more accessible, but I also feel it looks so much like Wikipedia. Why is that? Aside from that, I love the idea and could possibly see using a wiki of this type for Creative Writing (of all classes). Seriously! Think about how students could create a life for a fictional character through creating a wiki such as this. Endless possibilities.