There is quite a list but here are a few.
1. Borrow money on the credit of the US
Allows Congress to borrow money on credit to fund activities of the United States. Very important during times of war.
2. Establish post offices
Post Offices used to be much more contentious than they are today. Congress has the power to create post offices and postal roads
3. To declare war
Many do not realize this but the President cannot declare war. Congress must declare war for it to be a "legal" war and not an operation or police action.
4. Provide and maintain a Navy
Congress sets the budget and creates the Navy.
