I'm working with a team at the U of C who's testing an experimental hybrid rocket motor, due for launch this Summer.

Their main sponsor is supplying a payload that they want to test, but there is additional weight and space in the budget for something else. We don't have a definite limit from engineering yet, but think approx. 1 kg and 6 inches by 6 inches cylindrical. 

Does anyone have any ideas for a scientific / radio payload that would be interesting to fly?