I just launched a contest to give away 2 prototypes of the new Jetduino robotics interface board for the Jetson TK1. The Jetduino mounts on top of the TK1 and level shifts all of its GPIO, I2C, serial and SPI lines to 3.3V or 5v. It has Grove and 3-pin 2.54mm headers to make it very easy to connect commercial off-the-shelf sensors to the Jetson and communicate with them via Python or C++. It also has a built-in shield for any Mega or Uno form factor Arduino. It uses the GEN1 I2C line to communicate with the Arduino so you have easy access to all its features as well, like analog and digital read/write, servo control, serial communications and so on. The Jetduino is plug-n-play ready with over 100 Grove and RobotGeek sensors and actuators. There is also power filtering circuitry built in to make it easy to power your Jetduino and motors using batteries of different sizes and voltages.
You can find more details and enter the contest through the Jetduino product page http://neurorobotictech.com/Products/Jetduino.aspx.