Android 4.0 allows drag and drop of views. Lars Vogel shows you in detail how to do this.
Working With Fragments (mobile.tutsplus.com)
This tutorial shows how to use fragment-based designs to create a modular user interface for both, mobiles and tablets.
Another progress visualization (github.com)
Todd David has released an UI component that visualizes progress without a progress bar.
Android ORM for SQLite (greendao-orm.com)
GreenDao is an ORM that maps Java classes directly onto SQLite tables. No more tedious SQL wrapping.
With Chrome for Android Google has released a very fast and solid browser. One benefit for those who do web development is that it's update cycle is now decoupled from the Android OS update cycle.
Android Design Preview (plus.google.com)
Romain Nurik has released Android Design Preview, a little utility for Mac/Windows/Linux that'll mirror a portion of your desktop screen (such as your Photoshop canvas) to your USB-connected Android device.
Terminal IDE (market.android.com)
Terminal IDE is an expandable terminal application, with a full Java / HTML / Android development kit, that runs on your Android device.