At my university we have a course that goes over all the levels of abstraction between the hardware and systems-level UNIX programming. I never took the class, but I followed the course book on my own and it proved to be one of the most enlightening self-learning experiences I've had with programming. The book is Computer Systems: A Programmer's Perspective, and I highly recommend it.
I've found that even though I now spend most of my time programming in higher level languages, my understanding of C and assembly, compilers and debuggers, the virtual memory model and system memory hierarchy, and CPU architecture are still very valuable in helping me reason about my code and how it interacts with the rest of the system. I also still have developers at work on the C development team occasionally come ask me code questions, and often the answers to their questions come down to understanding one of the above better. If you can master multiple levels of abstraction you will be a much more effective developer.
I've found that even though I now spend most of my time programming in higher level languages, my understanding of C and assembly, compilers and debuggers, the virtual memory model and system memory hierarchy, and CPU architecture are still very valuable in helping me reason about my code and how it interacts with the rest of the system. I also still have developers at work on the C development team occasionally come ask me code questions, and often the answers to their questions come down to understanding one of the above better. If you can master multiple levels of abstraction you will be a much more effective developer.