Here’s my summary. Please correct if I misunderstood something.

Workers that must work without pay:

• Air traffic controllers
• most Transportation Security Administration employees
• U.S. passport agencies
• federal workers
• active-duty military service members

delay in services:

• Social Security
• VA
• other benefits

Services at Risk of Running out of funds:

• Supplemental Nutrition Program for Women, Infants, and Children (WIC) food program
• Supplemental Nutrition Assistance Program (SNAP) [food stamps]
• Federal Emergency Management Agency (FEMA)

Unknown:

• National parks
• National Weather Service

Not affected:

• Postal service