Surprising Things the U.S. Government Knows About You

Medical history, medications
The Social Security Administration keeps records of those enrolled in medicare, medicaid and those who have applied for disability benefits.
OSHA, the Occupational Safety and Health Administration, is likely to be on the case if you have reported a workplace accident. We have all signed the HIPAA form at the doctor’s office, but that may not keep our medical info as confidential as you’d imagine.
Law enforcement and child protection agencies, for example, may have access, though a subpoena may be required.
Ordering medications online or even just searching for certain conditions and illnesses are likely to leave a traceable trail in browser histories, which ISPs and others have been known to share with law enforcement and government agencies such as the FBI and NSA.
The government is also getting more efficient at inter-agency data sharing.