Camera Payload for Attitude Determination
A camera could be used for attitude estimation. For a satellite in Low Earth Orbit (LEO), it could be by finding the horizon of the Earth, and thus determining the pointing of the antenna based on this.

For a satellite deeper into space, it could be by the use of a star camera. This would take images of Space, and by comparing the position of the stars seen with an on-board star map, the orientation can be found.
Long time exposures could also be made, which can be used to determine the tumbling rate of the satellite.

Image processing and feature extraction would be used in all cases, however a limitation is present, since it has to run on-board a satellite with a size of 10x10x10 cm. This limits the computational power and storage capability.