OpenIntents

Library with Chart API, requires developer license.

http://www.keepedge.com/products/android_charting/

ZXing is an open-source, multi-format 1D/2D barcode image processing library implemented in Java. Our focus is on using the built-in camera on mobile phones to photograph and decode barcodes on the device, without communicating with a server.

Note also the project at http://www.onbarcode.com/products/android_barcode/

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

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/