One of my ideas from the good old Google Lunar X Prize days: Study single-celled organisms by a microscope, implemented in a CubeSat and send live stream videos of the single-celled organisms back to Earth:
Later I wanted to use water bears (tardigrades), launched in try state and only then supplied with growth medium in low Earth orbit. The oxygen supply was planned to be done by a small oxygen container, a separate oxygen chamber with exchange membrane or unicellular algae in the growth medium by photosynthesis. Here is one of the first drafts of the 'space microscope':
And the prototype:
To find tardigrades in Shanghai was more difficult than we thought. Finally we found this lazy specimen :
See also NASA's O/OREOS nanosatellite. The satellite was successfully launched as a secondary payload on STP-S26 led by the Space Test Program of the United States Air Force on a Minotaur IV rocket from Kodiak Island, Alaska on November 19, 2010 - one year after I had published the idea in a Google Lunar X Prize blog.