My vote is for the Art of Electronics, also. I've had it for years and years, but still use it all the time. In fact, today it is open to p77 (Basic Transistor Circuits).
j.
*A little story: I bought the Art of Electronics in 1994 at a Borders bookstore in Detroit, Michigan. It took me years to discover it, but I found that part of the book was missing in the Microprocessor chapter. Like 50 pages were missing, and the previous 50 pages were duplicated. But by that time I had moved to Milwaukee and there wasn't a Borders near me. Later I moved to Billings, Montana, where there IS a Borders, so I took it in and showed them; it still had the Borders price sticker on it and it was clearly a printing error, and though they were a little agitated and amazed that anyone would try to return a dog-eared, written-in book after nine years, they exchanged it with a new copy, which they had to special order.
I wonder if I have the record for returning a book?
Ok, it was a dumb story.