DartsMania
It is a Yii Framework (http://yiiframework.com) extension, so you'll need a running Yii install to use it.
Currently only supports the classic 301 game. - sorry :/
Installation
Step 1) extract the content under protected/extensions
Step 2) call it in a view like:
$this->widget( 'ext.dartsmania.dartsmania' );
Step 3) play!