OpenIntents

AGE is an open source, LGPL game engine for the Android platform that will push to streamline and standardize Android development for games with a focus on performance, size, and modular design.

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

Qualcomm's solution for P2P communication across platforms including Android:

http://developer.qualcomm.com/dev/alljoyn-p2p

Library with Chart API, requires developer license.

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

Android is an amazing platform, with great SDK for the developers to make rich application, though still for the absolute begineer the API are still hard to use, so I have made an extremely easy to use set of API for the Android SDK, with this the one who are extremely new to the development environment can still develop great applicataions.

Note: The library is compatible with Android 2.3.3 only right now.

For the documentation and the library go to: http://code.google.com/p/android-easy-library/

android-rss is a lightweight open-source (Apache 2.0) library to read parts of RSS 2.0 feeds. The library uses (Level 1) APIs such as android.net.Uri. The design features stream parsing with SAX. As a result, the memory footprint tends to be smaller compared to an equivalent DOM-based solution.

https://github.com/ahorn/android-rss

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

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/

Barcode scanner SDK made for fixed focus cameras as well as autofocus. Made by Big in Japan (ShopSavvy)

http://www.freebarcodescanner.com/

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

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

2D game engine base on cocos2d-iphone.

http://code.google.com/p/cocos2d-android/

A library for developers, wishing to work easily with Contacts,without knowing how a Content Provider operates.

http://androidlibs.com/contactslib.html

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

Library to access a CouchDB server
http://github.com/sig/DroidCouch

Client SDK for real-time games framework by Exit Games

http://www.exitgames.com/Download/Photon

Library with activities to connect with Facebook

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

Android library for visualizing real-time input data with horizontal scroll
http://graphwidget.android-libraries.com/

Library to add printing functionality to apps. Network printer, Wifi printer, Bluetooth printer.

http://www.iprintsdk.com/

Leading java based 3D game engine that also supports Android.

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

GDX is a simple Android game development framework that allows rapid prototyping on your desktop PC/Mac guaranteeing the same behaviour on your Android devices.

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

metagloss is an annotation-centric Android library for reducing boilerplate code. Relying on run-time parsing and compile-time code generation, metagloss provides facilities for mapping XML and databases to data objects, dealing with preference screens and working with DB queries.

SF Project page: http://sourceforge.net/projects/metagloss
Documentation: http://metagloss.sf.net

The Mobile Push API enables you to push content directly to one or more phones. SMS and HTTP technology are used for delivery, making it suitable for applications where it is important to ensure that the latest information always is available at the receiving end, without the need to frequently poll for updates.

https://labs.ericsson.com/apis/mobile-java-push/

An OAuth Library/application for Android which uses Content Providers in order to store OAuth data

http://github.com/novoda/oauth_for_android

Note, that you can also use SignPost for Android when just making OAuth calls (see http://github.com/kaeppler/signpost)

Open NFC is an open source stack implementing the NFC functionnalities, it consists of documentation and SDK add-on to enable RFID communication on Android.

http://sourceforge.net/projects/open-nfc/

PV provides software to deliver media services people will love. PV's software gives users greater access and control over their media experience, increasing the value of your services and helping you differentiate your brand.

A rich application framework for networked media applications and helps you:
Accelerate time to market
Reduce operational costs and resources
Improve the user experience
Brand your applications with a consistent look and feel

http://www.opencore.net/

Action: org.androidprinting.intent.action.PRINT
Input:
URI of the image to be printed, mime type of the image (must be of type "image/*")
Any application can use HP iPrint Photo for Android for printing images on nearby printers from Android phones.

HP iPrint Photo for Android phones: http://www.hp.com/global/us/en/consumer/digital_photography/free/softwar...
Wireless photo printing from your mobile device

RESTProvider handles all the HTTP querying and caching. Users can seamlessly interface with any Web Service API which provides JSON or XML as a response. To query a RESTProvider in an activity a user need only specify an endpoint and then query an APIs RESTful functions.

http://github.com/novoda/RESTProvider

The android app 'Path' has a very attractive action menu sitting on the left bottom corner of the screen. Satellite Menu is the open version of this menu. For the ones who didn't see path, the menu consists of a main button on the left bottom of the screen. When the user clicks on this button, a number of buttons are popped out of this button.

https://github.com/siyamed/android-satellite-menu/

SocialLib aims to make the development of Social apps much more easier. Currently, Social Lib provides access to the following social networks : Facebook, Twitter, Google Buzz, LinkedIn.

http://androidlibs.com/sociallib.html

Spring Android is an extension of the Spring Framework that aims to simplify the development of native Android applications.
Contains a Rest Client, a Commons Logging adapter

http://www.springsource.org/spring-android

Charting library for Android, provides a CHART Intent to return a picture of your custom data.

http://www.steema.com
https://market.android.com/details?id=com.steema.teechart.android

final Intent intent = new Intent("com.steema.teechart.android.CHART");
intent.setType("text/*");
intent.putExtra("Header", "Hello World !");
intent.putExtra("Style", "Bar");
intent.putExtra("Text", new String[] { "Apples", "Bananas", "Kiwis" });
intent.putExtra("Values", new double[] { 45, 23, 12 });

public void onActivityResult(int requestcode, int resultcode, Intent intent) {
if (resultcode == RESULT_OK)
final Bitmap bitmap = ChartIntent.getChart(requestcode, intent);
}

TeeChart provides complete, quick and easy to use charting .NET, Java, ActiveX / COM, PHP and Delphi VCL controls for business, Real-time, Financial and Scientific applications.
Full source code available, visit us at www.steema.com

TeeChart for Java v.2 Charting component Library ships with 100% sourcecode in Android, AWT/Swing and SWT formats. It supports major Java programming environments including IBM Eclipse, Sun NetBeans, IntelliJ IDEA and Oracle JDeveloper.

The charting library offers 50 Java Chart styles (in 2D and 3D plus multiple combinations), 38 mathematical functions and 20 Chart tools components for additional functionality including dragging of series marks, annotation objects, cursors and manual trend lines, coloring bands, etc.

Charting styles:

Line (Tape), Points (Scatter XY and XYZ 3D Scatter), Area (Stacked and negative), FastLine (real-time speed), Horizontal Line, Bar and Horizontal Bar (Stacked and negative), Pie (Exploded, partial angle), Shape (Cube, Pyramid, Cylinder, etc), Arrow (Callout), Bubble, Gantt, Candle (Finantial OHLC High-Low), Donut (Exploded Doughnut), Volume (Stock), Bar 3D, Points 3D, Polar, Radar, Clock, WindRose, Pyramid, Surface (XYZ Grid Mesh), LinePoint, BarJoin.class, ColorGrid, Waterfall, Histogram, Error, ErrorBar, Contour (Contouring Levels), Smith, Calendar, HighLow, TriSurface (Voronoi triangulation of arbitrary XYZ points), Funnel, Box (Box Whisker), Horizontal Box, Horizontal Area, Tower, Point and Figure, Gauges, Vector 3D, Map (Mapping GIS), Bezier, Bar with Image, IsoSurface (Auto Leveled XYZ Mesh), Circular Gauge, Linear Gauge, Vertical Linear Gauge, Horizontal Histogram.

Feature Summary:

50 Chart styles (in 2D and 3D plus multiple combinations) including Gauges
38 mathematical functions
100% sourcecode for Android, AWT/Swing and SWT
Run-time Editor, Gallery dialogs
20 Chart Tool components for additional functionality, like dragging series marks, annotation objects, cursors and manual trend lines, coloring bands, etc
Chart Grid component to manage data
Multiple-axis support both horizontal and vertical
Customisation of axis labels and legend items
Great cosmetic properties for all texts and drawings
Complete set of chart styles, both in 2D and 3D
Live and animated zoom and scroll. Multi-touch and mouse wheel supported
2D and 3D
Custom drawing canvas
Extensive demos
Design and runtime integrated Chart and Series editor
New improved Javadoc format help plus Tutorials
Many new visual features, transparency, colour gradients, gray-scale.

Mathematical and statistical functions:

Add, Subtract, Multiply, Divide, High, Low, Average, Count,
Momentum, Momentum Division, Cumulative, Exponential Average, Smoothing, Custom User Defined, Root Mean Square,
Standard Deviation (StdDeviation), Stochastic, Exponential Moving Average, Performance, CrossPoints, Compress OHLC,
CLV, OBV, CCI, Moving Average, PVO, DownSampling, Trend, Correlation, Variance, Perimeter, CurveFitting,
ADX, Bollinger, MACD, SAR, RSI, Histogram Function.

Library with activities to connect with Twitter and Demo Twitter Project

https://github.com/brione/Brion-Learns-OAuth

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

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