speaking of the Simple Math of Everything, that sounds like a great Less Wrong community project, no? I have no idea what the money from sales would be used for - maybe donations to SIAI or something.
Agreed, fully!
This should be discussed in a top level post. Such a document would be a valuable contribution to the intellectual world.
A wikibook might be a good medium for this kind of community project. The LaTeX book gives an example of how well these can turn out.
Related to: The Simple Math of Everything, Your Strength as a Rationalist, Teaching the Unteachable.
Eric Drexler wrote a couple of articles on the importance and methods of obtaining interdisciplinary knowledge:
This topic was discussed intermittently on Overcoming Bias. Basic understanding of many fields allows to recognize how well-understood by science a problem is and to see its place in the structure of scientific knowledge; to develop better intuitive grasp on what's possible and what's not; and to adequately perceive the natural world.
The advice he gives for obtaining general knowledge feels right, even for studying the topics that you intend to eventually understand in depth: