Stanford Space and Systems Development Laboratory, where students are developing 4x4x4 inch satellites designed for standardized production, using materials you might not expect for an object that will end up in orbit.
In 1965, the United States launched a small, experimental reactor into space. It shut down after 43 days of operation, but remains in orbit. It'll re-enter the Earth's atmosphere in about 4,000 years.
At MIT's Computer Science and Artificial Intelligence Laboratory, the Robust Robotics Group works on devices meant to behave autonomously in new environments, and with limited information.