They just launched a big report which is about fees paid by pharmaceutical companies to doctors to promote their drugs, done with five leading media partners (NPR, Consumer Reports, Chicago Tribune, Boston Globe, Nightly Business Report on PBS.)
The story explains how drug companies pay hundreds of millions of dollars resulting in nearly seven billion dollars in fines so far. They often pay doctors with dubious records, and sometimes in violation of FDA regulations.
Beyond this, ProPublica's database of 17,000 names is searchable by doctor, enabling patients across the country to see if their doctor may be taking money that could be influencing decisions on what to prescribe. That's a big deal right there for journalism in general, allowing others to dig up facts that affect us.