OpenIntents

Library to create and manage databases through xml resources.

Read more at http://www.brighthub.com/mobile/google-android/articles/52883.aspx

http://code.google.com/p/androiddataframework/downloads/list

Android Chart Engine, requires developer license.

http://www.artfulbits.com/Android/aiCharts.aspx

The TTS library for Android (Text-To-Speach)

http://code.google.com/p/eyes-free/

JSON marshaller/unmarshaller for Java that runs on Android

http://fisheye.codehaus.org/browse/jackson/

Calculon is a testing DSL for Google Android. It allows you to write functional story based tests.

http://github.com/kaeppler/calculon/

Angle is aimed to be a way to develop 2D games using OpenGL ES on Android providing as much speed as possible. The engine is entirely coded in java so you can overload every object for your convenience.

http://code.google.com/p/angle/

Great collection of reusable code for various objectives.

http://github.com/commonsguy/cw-android

Rokon is an open source OpenGL 2D game engine for Android mobile devices.

http://code.google.com/p/rokon/

Droid-Fu is an open-source effort aiming to collect and bundle solutions to common concerns in the development of applications.

Droid-Fu offers both support classes meant to be used alongside existing Android code, as well as self-contained, ready-to-be-used components like new adapters and widgets.

http://github.com/kaeppler/droid-fu

A very thin yet complete xmlrpc client side library for Android platform.

http://code.google.com/p/android-xmlrpc/