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
• Troubleshooting Common Issues
• 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 Tips and Q&A
• RottenTomatoes Networking Tutorial

• Working with Input Views
• Handling ProgressBars
• Implementing a Heterogenous ListView
• Creating and Using Fragments

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

• Customize Appearance With Drawables
• Styles and Themes
• Cloning a Login Screen Layout Guide
• Customizing the User Interface

• Android Unit and Integration Testing
• Robolectric Installation for Unit Testing

• Endless Scrolling with AdapterViews
• Common Navigation Paradigms
  • Fragment ActionBar Tabs Guide
  • Fragment Navigation Drawer Guide
  • ViewPager with FragmentPagerAdapter Guide
• 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!