Library
In the space
Electronics
- Foundations of Analog and Digital Electronic Circuits, Anant Agarwal & Jeffrey H. Lang
- The Principles of Computer Hardware, Alan Clements
Security
- Applied Cryptography, Bruce Schneier
Natural/Spoken Language
- Step By Step in Esperanto - For those who like their languages easy and constructed.
On the web
Machining
- Guerrilla guide to CNC machining and resin casting: Volume 1: Basic theory and preparations, Volume 2: Real-world projects
Electronics
- The Giant Internet IC Masturbator (IC pinouts without pages of ads)
- Native USB for AVR
- Analog Circuit Design (superb book about analog design by Jim Williams)
- The Art and Science of Analog Circuit Design (more in a similar vein)