Ask HN: Where do you find examples of complete projects for learning?

I find that there are a lot of resources in learning the syntax of a new language but less so in learning the project structure and basic conventions. Books are great guides but they are often spend a long time going through one or several projects that showcase only very specific applications while neglecting others. I would like to find a resource I can use to find examples of well written, production level, non-trivial projects of varying complexity. Ideally, there should be some basic guide through the layout of the project structure and how different classes relate to each other. Although I come across many open source projects, I find that they usually aren't documented with the perspective of being used as learning tools. Also, it would be beneficial if the list was curated to ensure that the code is written well and can serve to showcase a particular principle (social networking, database dependencies, etc).