In the beggining was the 555.
I did a lot with that little chip. My brother purchased a book on the 555 - giving lots of examples for its use as a monostable or an astable. Ah the memories.
Then I got interested in logic circuits (as, I learned, appear in computers...) and things that light up, go beep and occasionally go bang (when you accidentally short those two pins..).
After that was Horowitz & Hill. In my considered opinion one of *the* best books on electronic circuits and circuit theory. A must-have pre-read if you want to go any further (ie before Boylestadt & Neshelsky for instance).
And then was the LM317, LM200, Electronics at 'A' level (part of my Physics course provided by the NAEB). Then, a degree in electronics. Didn't like the analogue, liked the digital and wished circuit theory was like computer programming (after programming in 'C' for longer than I care to remember). That's probably why I moved onto more computing-based subjects at university.
However now I'll happily dabble with electronics again for whatever purpose. Except power electronics. Boom bang etc..