eureqa

Eureqa (pronounced "eureka") is a software tool for detecting equations and hidden mathematical relationships in your data. Its goal is to identify the simplest mathematical formulas which could describe the underlying mechanisms that produced the data.
-- from the eureqa site

wnyc's radiolab show on limits of science that talks about eureqa
with pointers to referenced research:
http://www.wnyc.org/shows/radiolab/episodes/2010/04/16/segments/149570
http://ccsl.mae.cornell.edu/sites/default/files/Science09_Schmidt.pdf
http://ccsl.mae.cornell.edu/eureqa
http://www.mae.cornell.edu/lipson/