Vultures are the only non basic and non worker unit that does not require gas for production. Some do not bother using vultures any more due to the concussive damage and they pose no use.
Wrong! Vultures with their cost have their uses. They cost only 75 minerals very cheap and their upgrades make them worth using in the battlefield.

• With the speed upgrade, vultures can sneak in enemy bases and kill off the workers. Vulture grenades are very effective against workers.
• Vultures are good for hit and run tactics and are good versus zerglings and terran infantry.

• Try placing the mines at the entrance of an opponents base.
• Use mines in resources possible for expansions.
• Place spider mines in heavy traffic passages.
• Try attacking with vultures and retreating in spider mined ground, this way if your opponent will be lured into a deadly territory.