We absolutely love The Art of Electronics by Paul Horowitz and Winfield Hill. So much so, our Ladyada (Limor Fried, founder and engineer of Adafruit) scored a review copy and even gives her commendation on the back cover! Here's what she had to say:

"Who among us has not kept a cherished copy of AoE on our workbench throughout our careers? Engineers, hackers and makers of all stripes, rejoice for the third edition … has been worth the wait! Packed with tons of delicious knowledge to navigate electronics in both work and hobby. An encyclopedia of electronics knowledge, [The Art of Electronics] is a pleasure to read through for tips and tricks and is a unbeatable resource! Take a day out to read a chapter - you will learn things you didn't even know you didn't know. Or, refer to the pinouts, diagrams, and techniques as necessary to guide you through a difficult project. If you think electrical engineering is magical then you must pick up this tome!" 

Limor 'Ladyada' Fried, Adafruit Industries

The third edition features enough new info that's it's worth buying.  Here's the description from the Art of Electronics folks themselves:

At long last, here is the thoroughly revised and updated third edition of the hugely successful Art of Electronics. It is widely accepted as the best single authoritative book on electronic circuit design. In addition to new or enhanced coverage of many topics, the Third Edition includes: 90 oscilloscope screenshots illustrating the behavior of working circuits; dozens of graphs giving highly useful measured data of the sort that's often buried or omitted in datasheets but which you need when designing circuits; 80 tables (listing some 1650 active components), enabling intelligent choice of circuit components by listing essential characteristics (both specified and measured) of available parts. The new Art of Electronics ​​retains the feeling of informality and easy access that helped make the earlier editions so successful and popular. It is an indispensable reference and the gold standard​​ for anyone, student or researcher, professional or amateur, who works with electronic circuits.

Clocks in at a whopping 1,220 pages with 78 tables - so prepare yourself for a very long and informative book club!