Have you ever thought that it would be awesome to combine the capabilities of Lego with Arduino? This is exactly what TiagoStantos has done with his Arduino controlled Lego train system.
The Arduino is used to enable the train to sound a whistle as it approaches the station and when stop at the platform. The project includes full code examples and is sure to inspire you to create more interesting combinations between Lego and Arduino.
To get started learn how you can control your Lego train system with Arduino checkout the following link.