If you have free time to learn something new for the sake of learning rather than for grades, diploma, degree or qualification:
Red Rock Eater News Service – http://polaris.gseis.ucla.edu/pagre/rre.html
This is mostly about social and political aspects of computing and networking.
Troubleshooters.com(R) – http://www.troubleshooters.com/troubleshooters.htm
If you, like everyone, need to troubleshoot something such as a malfunctioning car or a mysterious software bug, read what this Web site has to say about being more productive troubleshooter.
Perfecting the art of building embedded systems – http://www.ganssle.com/
For those fortunate to have a career developing software for embedded systems.
Several articles have relevance also for people, who do not do embedded development.