Seven-languages-seven-weeks is a project mainly written in IO and RUBY, it's free.
Following along in bruce tate's book by the same name. Keeping my work in here
Seven Languages in Seven Weeks I'm reading this book and following through the exercises. My worksheets for the problems are all here in github.
[http://www.pragprog.com/titles/btlang/seven-languages-in-seven-weeks]