Rosetta Code

Description
Rosetta Code is a repository for code examples that go beyond the traditional "Hello World!" example. A series of tasks are listed, and visitors to this site are asked to complete the tasks in the language of their choice. The tasks are intended to allow users to learn new programming languages based on old ones, or to compare programming languages. There are over 550 tasks with varying complexity and programming subject matter which may have examples in over 400 languages. There are even four projects: three simple language interpreters and a text-based dungeon RPG. Besides tasks there are encyclopedic pages that talk about programming languages, operating systems, programming paradigms, and computer science terminology. The site has more than 30,000 code samples across all tasks and languages (seen in the "Implemented in language" property here).