HI all
At WikiSym, there where two sessions about what data researches would like to have for their work: http://www.wikisym.org/ws2010/What+data+to+collect and http://www.wikisym.org/ws2010/XML+dumps+and+research+needs+for+WMF+projects.
From that, Ariel Glenn compiled a wiki page
http://www.mediawiki.org/wiki/Research_Data_Proposals and asks reasearchers for input about what data they would need.
So, go ahead, add to the wish list!
-- daniel