A few weeks ago the Microsoft Office blog re-announced a move and updates to the Patterns & Practices work that had been living on CodePlex. You can read up on their announcement in this blog post: Office 365 Development Patterns & Practices Launched.
Previously the Office App Model Samples (Office AMS for short) team focused on creating code samples for customers that were looking to perform common tasks we were used to performing with fully trusted code in the app model. This consisted of scenarios, samples and solutions. These samples were posted to CodePlex, zipped up and posted for customers to download.
However they have moved the entire project over to the OfficeDev GitHub organization. Since they have moved things over you’ve seen a lot more people start contributing to the project… it’s amazing how GitHub really fosters this type of peer involvement.
I’d encourage you to check out what they have included in the latest source. This P&P work is the best output I’ve worked with that comes from the P&P groups at Microsoft. What you’ll find are a bunch of great examples, but also one project that is reused across most of them. The OfficeDevPnP.Core project contains a ton of extension methods and other utilities that extend the CSOM with tons of extra functionality.