QuiteSleep is an application for Android 2.0+ which manages your incoming calls when you're busy, sleeping, or doing anything between two time slots in any day of the week.
QuiteSleep can block a list of callers or even other different incoming calls and send an SMS or e-mail with a predefined text to notify you're busy, sleeping, etc.
QuiteSleep is completely FLOSS (Free Libre Open Source Software) and is distributed under GNU GPLv3 license, which you can distribute it, modify it, copy it and use it as you wish. All icons and fonts is also under free software licenses how CC-BY-SA v3, GNU GPL and Public Domain.
QuiteSleep introduces db4o object oriented database, so you can see how works in Android system for your use in your own projects.