The Android Mono project allows you to run .NET applications on the Android platform!

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

An Android application that intercepts incoming text messages and displays them in a popup window (activity). The popup window shows the contact the message came from and their contact photo (if there is one) as well as the content of the message. Directly from the popup the user is given the option to Close the popup (marking the message read) or Reply to the message (using a system intent).

The more recent versions of SMS Popup also have a full notifications system built in – this allows a user to disable the built in messaging app notifications and use those from SMS Popup. The notifications system has additional options such as custom vibrate pattern, custom LED color and the ability to remind the user of a missed message in case they missed the notification the first time it played.

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

BistroMath is a specialized calculator for solving “bistromatic” problems which involve numbers on a a waiters check-pad and people in restaurants.

Given the amount on the bill, we can quickly calculate tax, tip, how to divide equally among N people or convert into another currency.

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

Countdown Alarm++ application for the Android mobile OS.

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

Android email client for SMS to email gateways.

http://code.google.com/p/android-sms-email/

This is a port knocking client for Android in very early stages!

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

GeoBeagle is an Android application for geocaching and letterboxing.

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

A simple tricorder for Android, using your phone’s real sensors to detect magnetic fields, gravity, etc. Detect buried powerful magnets! See the passing gravity wave from a distant collapsar on your phone screen!

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

This project’s objective is to develop a pure Java implementation of the Android’s Dalvik virtual machine.

http://code.google.com/p/android-dalvik-vm-on-java/

A collections of utilities for cleaning up your contacts.

http://code.google.com/p/android-contacts-cleanup/