Sites such as wikipedia.org, open-site.org or dmoz.org all are part of a neat trend in web development: self-managing web space, where members contribute and edit content themselves.
This idea is not new. Web discussion board have a similar (although much simpler) dynamic, and have been around almost as long as the web itself. However, the idea of a directory or hierarchy of information (like a web-based encyclopedia) that is mostly publicly-editable and non-commercial, is really kinda cool.
Actually, I think that Wikipedia (www.wikipedia.org) is closest to the original vision of the Web as I understood it from reading the book by Tim Berners-Lee titled "Weaving the Web". In that book, he described the way that the web would work, and how information between documents could be interlinked and traversed by users in real-time. It sounds so much cooler when he says it in his book. When I say it, the words just kinda lay there flat...
Wikipedia.org is a sort of free-for-all web encyclopedia, where anyone can volunteer to create or edit information for the rest of the web to see. I have encountered some interesting and well-written articles in Wikipedia on subjects such as the Internet, ESL, and of course, DEVO :)
The Open Directory Project (dmoz.org) is Netscape's effort to build the largest hand-edited directory on the web. Unlike Wikipedia, "ODP" is edited by volunteer editors, who use their own discretion and god-like system access to add, remove or approve directory categories or contents. You can submit suggestions for content to ODP for free. I have heard that becoming an Editor on ODP can take a long time or be a bit difficult. I think it is an extremely busy and active web service.
Open-site.org is referred to as a "sister site" of ODP. Also a directory, it is slightly different in that it allows longer, more encyclopaedic articles and a greater variety in different "styles" of submission. It is also easier to become an editor. I am an editor there, although I have yet to decide exactly what I will do with my new-found power.
All these three sites are extremely well-ranked in Google, with front pages that have a pagerank of 9 out of 10, which is pretty dang high.