http://code.google.com/p/apps-for-android/
A collection of useful, open source applications that demonstrate features of the Android platform:
Amazed: A simple but addictive accelerometer-based marble-guidance game.
AndroidGlobalTime: a full representation of the Earth that you can spin around.
AnyCut: A utility that lets users create Home screen shortcuts to nearly anything in the system.
Clickin2DaBeat: A game that mashes up YouTube with custom rhythm-game logic.
DivideAndConquer: a game in which you must isolate bouncing balls by creating walls around them.
HeightMapProfiler: A simple 3D performance testing tool that renders a 3D height map.
LOLcat Builder: O HAI. I CN HAS CHEEZBURGER?! IM N UR PHONE, CAPTIONIN UR PHOTOS.
Panoramio: An app that shows you nearby photos and points of interest.
Photostream: An app that lets you view photostreams from online photo-hosting services.
Radar: A radar-style relative location display view, used by Panoramio and others.
RingsExtended: A utility that provides enhanced control over ringtones.
Samples: Miscellaneous examples showing features of the Android platform (among which OpenGL ES).
SpriteMethodTest: An application that compares the speed of various 2D sprite drawing methods.
Translate: Translates more than 150 language pairs with Google's translation service.
WebViewDemo: How Java and JavaScript can call each other inside a WebView.
WikiNotes: A wiki note pad that uses intents to navigate to wiki words and other rich content stored in the notes.