For those interested in global health, we've tried to collate as much data as possible at http://ghdx.healthdata.org/ (disclosure: I'm the director of data science at IHME, which hosts this).
Note that most of this data is population level epidemiologic and administrative stuff, not the detailed biomedical measurements I see most people requesting - but I promise you there's some really interesting things that can be done with it nonetheless!
Note that most of this data is population level epidemiologic and administrative stuff, not the detailed biomedical measurements I see most people requesting - but I promise you there's some really interesting things that can be done with it nonetheless!