There a lot of resources out there for improving your Ruby or Javascript skills. http://www.codecademy.com/learn has some great content. https://peepcode.com/ is great as well.

Run through every tutorial you can find, improve upon the code in some way, then write your own blog post about it.

If you're really wanting to jump into some real-world code, checkout some node.js and ruby projects on GitHub and start contributing. This can be as simple as fixing/updating documentation or filing bugs. Improving tests is a great place to start.