Long story short, I found a bunch of mdb files with personal information about people's ambulance rides. I reached out to EMS and they were very nice and took the drive back with them. A few weeks later I got a scary lawyer email asking me to submit all my computers for a search because I hacked their security to get the data.
It eventually turned out OK, but the moral of the story is that I will never again do the right thing if I happen to discover a problem that makes a large entity look bad.