Cliffnotes are references giving you the "most important" Android topics with brief explanations and relevant code snippets. The idea here is to distill the concepts down to shorter cliffnotes so you don't have to "read the book".

• Android Directory Structure
• Organizing your Source Files
• Using String Resources
• Constructing View Layouts
• Defining Views and their Attributes
• Working with the Soft Keyboard
• Using an ArrayAdapter with ListView

• Basic Event Listeners
• Defining the ActionBar
• Displaying Toasts
• Using Intents to Create Flows
• Common Implicit Intents

• Creating and Executing Async Tasks
• Sending and Managing Network Requests
• Converting JSON to Models
• Persisting Data to the Device
• ActiveAndroid Guide

• Working with Input Views
• Handling ProgressBars
• Creating and Using Fragments

• Loading Contacts with Content Providers
• Using Hardware, Sensors and Device Data
• Google Maps Fragment Guide

• Endless Scrolling with AdapterViews
• Common Navigation Paradigms
  • Fragment Navigation Drawer Guide
  • Fragment ActionBar Tabs Guide
• Customizing the User Interface
  • Cloning a Login Screen Layout Guide
  • Drawables Guide (Styling Views)
  • Animations for Layouts and Views
• Sharing Content with Intents Guide
• Must-have Libraries Guide
• Implementing Pull to Refresh Guide
• Implementing a Horizontal ListView Guide

If there's anything else, feel free to suggest new cliffnotes and/or help contribute to them!