I was thinking of a sidebar featuring:
- Latest jobs in Robotics (similar to stackoverflow)
- Interesting news from around the world in the field of Robotics
- A list of upcoming conferences like ICRA, CVPR, etc.
As for the layout, I agree that something uncluttered yet elite, with some art featuring robots in the background would be just great.
EDIT: For the layout, the background could contain images of a code snippet(to portray that programming questions related to robotics are allowed), circuit schematic(to portray that certain problems regarding circuitry for motor control), point clouds(to portray that computer vision/navigation/SLAM questions are welcome), and a few robotic avatars (sci-fi or currently in market) to give the overall feel of having entered a 'Robotics' Q&A community site.