Here are some TurtleBot accessories we have been working on developing.
A pan tilt system for moving the Kinect without moving the robot to help build accurate 3D maps.
The base can also be used to mount other sensors such as 2D laser scanners to a Robotis RX-28 servo, a base for an AX-12A servo is in development.
Perhaps if your robot is interested in getting a job as a waiter, it may be interested in this cup holder for beverage delivery tasks.
Having now designed one, it's somewhat surprising how much engineering goes into making a decent cup holder.
So what accessories does your robot need?