1. A system for organizing knowledge in such a way that users can find knowledge, learn from it, and add to it as needed, comprising: a knowledge base comprising knowledge, meta-knowledge that was created at a time of entry of said knowledge, and meta-knowledge in the form of one or more annotations that accumulate over time, said annotations including any of, but not limited to, usefulness of said knowledge, additional user opinions, certifications of veracity of said knowledge, commentary by users, and connections between said knowledge and other units of knowledge; a set of user tools comprising one or more tools for entering said knowledge, said meta-knowledge, and said one or more annotations into said knowledge base; and a user learning model comprising any of information on a user's needs, capabilities, knowledge, and preferences, said meta-knowledge stored in said knowledge base, and generalized knowledge about how people learn.