http://www.youtube-mp3.org/

YouTube-mp3.org is the easiest online service for converting videos to mp3. You do not need an account, the only thing you need is a YouTube URL. We will start to convert the audiotrack of your videofile to mp3 as soon as you have submitted it and you will be able to download it. Different from other services the whole conversion process will be perfomed by our infrastructure and you only have to download the audio file from our servers. Because of this our software is platform-independent: You can use it with your Mac, a Linux PC or even an iPhone. All our conversions will be perfomed in high quality mode with a bitrate of at least 128 kBit/s. Do not worry, our service is completely free. We need approximately 3 to 4 minutes per video.

Follow this link to discover the dimensions of the arduino boards.
This will help you build your own shields.

http://blog.protoneer.co.nz/arduino-uno-and-mega-dimensions/

how to simulate  Arduino with Proteus

http://www.youspice.com/ys/gettingstartedwithproteus.3sp?pageNum=0