Cool Hardware/Devices that can be programmed in .NET?

I'd love to start writting managed code for external devices and sensors. Are there any devices that come to mind that can be coded against using .NET? Any suggestions?

Edit: The main thing I'm trying to do is learn how device programming works. No better way to do that in my opinion than to try to do something fun and cool.

Lego Mindstorms NXT

• http://mindstorms.lego.com/
• http://en.wikipedia.org/wiki/Lego_Mindstorms_NXT
• http://nxtnet.codeplex.com/

The Netduino just came out, and it uses the .NET Micro Framework: --> http://www.netduino.com/