Everything2 is not a wiki but it functions similarly. Users can make a write-up about any topic and then other users can add onto that write-up forming a "node" but they cannot change what the first person wrote. The community there focuses on all kinds of writing, including personal "daylogs" which act almost like a bliki. For a time, it was considered an alternative or competitor to Wikipedia.
- DMOZ, another collaborative project which is somewhat similar to a wiki.