Here you'll find AirShow a tool for sending images and your desktop (as images not AirPlay mirroring) to the Apple TV.

DOWNLOAD HERE

There is also airplay.php and airplay.jar, libraries for PHP and Java. The Java library also requires JMDNS if you want to support searching/bonjour auto discovery.

Basic PHP/Java example for sending an image added here http://code.google.com/p/open-airplay/source/browse/#svn%2Ftrunk%2FPHP Send a photo:

php airplay.php -h hostname[:port] -p file
java -jar airplay.jar -h hostname[:port] [-a password] -p file

Steam desktop:

php airplay.php -h hostname[:port] -d (mac only)
java -jar airplay.jar -h hostname[:port] [-a password] -d

Open Source

• PascalWAirplayer - A Python based library
• Play2Wifi - An AirPlay server also in Python
• Totem Plugin AirPlay - Plugin enabling AirPlay video playback in the Totem media player (Python)
• elcuervo/airplay - Airplay bindings to Ruby
• Airstream Media Player - C# based AirPlay screen for windows and AirPlay server source code
• xmms2-plugin-airplay - Debian AirPlay library
• AirPlay NMW - AirPlay plugin for Network Media Tank written in C
• AirMac - Turns you Macintosh into an Airplay receiver (Objective C)
• AP4J - Java AirPlay video client

Applications

• Beamer - Send any video to an AppleTV
• AirParrot - Send the screen of your Mac to an AppleTV (AirPlay Mirroring)
• AirServer - The best app for turning your Mac into an AirPlay screen.
• Reflection - Turn your Mac into an AirPlay screen.
• Banana TV - Another app to turn your Mac into and AirPlay screen
• Erica's Air Play Utilities - A collection of Mac utilities for streaming video and photos (not open source)
• doubleTwist AirSync - Stream music/videos from your Android phone over AirPlay

Websites

• Stream DVDs - Stream DVD's from a Mac using Erica's AirFlick and VLC
• Stream Desktop - Stream your Mac's desktop using Erica's AirFlick and VLC (Audio not supported due to limitations in VLC)
• lifehacker - Make your entire home AirPlay compatible