Every coach needs a clipboard and a whistle. While I don't know about a whistle, I can certainly point you in the direction of an ultra modern clipboard. The E-Ink Electronic Coach Playboard uses E-Ink technology. It's perfect for chalking out strategies for multiple games like baseball, basketball, football, soccer, etc. It holds pre-loaded templates of the field/court. All you have to do is choose your game and start drawing the moves with your finger. So quite a handy clipboard we have here. It's designed by Gordon Yeh for Iota Creations.

[Yankodesign]