"The ISS hat two mission objectives, (I) to bring the international community together for collaboration and friendship - this has been accomplished very well, and (II) to do some meaningful science up there, which has not been accomplished at all as of yet. Thus, it's your job to invent meaningful experiments to make the ISS more than a toy." (in the direction of the present students, not the Columbus module team)
What do we learn from this? They need and want input, and they need justification for the expense. The stuff shown here is thus entirely within the official line of the ISS teams.
They're usually running between 100-150 "experiments" at any given time. Most of these do meaningful science. As we all should know, research and science doesn't always lead to something tangible though, but even in the cases it doesn't, it tells a lesson.
Wikipedia lists some of them, http://en.wikipedia.org/wiki/Scientific_research_on_the_Inte..., and just few weeks ago, results from the AMS (http://en.wikipedia.org/wiki/Alpha_Magnetic_Spectrometer) provided some of the most tangible measures we have of dark matter.