Olive oil is the most common dipping oil for Italian bread. It is served in many restaurants with a swirl of balsamic vinegar in the middle. Many recipes for bread dip use olive oil as the main ingredient.
A simple olive oil dip for Italian bread from AllRecipes.ca is a small plate of olive oil topped with garlic, drizzled balsamic vinegar, sprinkled Parmesan cheese and a pinch of oregano. The Food Network's recipe for garlic oil says to put the olive oil in a pan over medium heat, and add 4 cloves of garlic. Keep the oil over medium heat for five minutes. Let it steep for an hour, and then strain out the garlic cloves.