I'm trying to move from beginners theory to practical applications and have since ordered and received David Cooks "Robot Building for Beginners"
Amazon.com: Robot Building for Beginners (0689253154458): David Cook: Books. There's a review of this book in a thread on this site.....he shows how to build a line follower(like what you were asking)...the downside is lack of math and the builds are done without microcontrollers...he uses logic chips. I think his second book "Intermediate Robot Building"
Amazon.com: Intermediate Robot Building (0689253593738): David Cook: Books discusses microcontrollers, though I don't know how much...probably need a second book for that, ofcourse. I also believe his second book goes in depth with robotics and the circuits for them....you may prefer just electronic circuits but this will teach you how to build circuits for a load, whether it's an led, speaker, or motor.
Other suggestions would be Elektor Mags, Make Mags, Servo Mags, Nuts and Volts Mags, etc.
The hard part is finding something that doesn't only show you a schematic and what the purpose of the circuit is, but step by step explainations as to why a certain component is placed in the circuit and a supplement for that component if you don't have one just like it...David Cook's books seem to do just that...After that I feel you'll get a better understanding of why and how a circuit is designed the way it is to help you with your own circuit designs. I ordered both his books at the same time and Chapters cancelled the second book cause they were out of stock....sooooo, send it when you get it!! What's that all about? Now I won't get free shipping. I haven't read through his book in detail to give an accurate review, soon though.
I used the "All New Electronics Self Teaching Guide" to learn electronics, since I'm a beginner and found the book helpful, but I found mistakes in his answers and a frustration when I couldn't figure out how I came to a different answer when he didn't show his math. Overall, it was helpful for practicing calculations. But ofcourse, one needs to read an intermediate level book for a wider and detailed electronics theory.
Just my two cents.