I grew up learning programming on a Commodore 64, where getting anything done meant twiddling bits and writing to registers of various hardware devices. Writing device drivers today can provide the same sort of thrill, since the work is quite similar. A lot of my time in high school and college in the 90's was spent learning all about UNIX and Linux, so it feels very natural today when I develop user-space tools that bring value to the user. Outside of nostalgia, there's plenty of bleeding-edge work to keep things interesting -- audio/video processing, extending platforms such as Android, security, etc.