Rosetta Code is an incredible resource for learning programming languages and building your skill as a developer by understanding how different languages accomplish the same task.
If you know one language and are interested in another, Rosetta Code contains a huge range of code examples across different domains that you can view, compare, and even contribute to.
Spend some time looking through the code. Maybe you'll learn something new. Maybe it will spark an interest in another programming language or style. Maybe you'll contribute to future developers learning.
I could keep praising it, but really I want you to go experience it.
Enjoy!