Marcia is right, the ISS experiments are directed by what is expected to produce a usefull result to science and industry. And even though we can't predict which experiments will be most usefull in advance, even negative results narrow the field. some examples of this are:
Experiments on supercritical colloids, of interest to industry, pharmacuticals, etc.(http://spaceflightsystems.grc.nasa.gov/Advanced/ISSResearch/MWA/BCAT/)
Results from experiments on protien crystals, medical science and biochemistry driven.
(http://scripts.iucr.org/cgi-bin/paper?S0907444902021443)
Follow up work on the discovery that micro-G affects salmonella behavoir.
(http://science.nasa.gov/headlines/y2009/06may_salmonella.htm)
If I've posted any of that before my apologies, I don't keep track of what I post very well.
Space/Science » in reply to re: ISS
ISS experiments: