as in the title. Be it textbooks, bios or anything else. Somewhere I've heard that a couple of books in a given subject can give you quite a good understanding of it.
It does not have to be a niche either; I am interested in hearing about your favourite general psychology or biotechnology books just as well; I hope we can exchange recommendations about how to dive into a given field.

For me, I'd say that to get a taste of Computer Science from the metal to high level concepts, I'd go with:

• Introduction to Algorithms by Cormen et al. - for many it's bible of algorithms designs, I also enjoyed it very much (and I like to think that it was not only because of widespread aclaim)
• CODE by Petzhold - for people who like to understand every part of the system they build; it goes through the process of building a computer, starting with logic gates and ending with fully working Turing machine.