Vaayu is the epithet of the wind god. He is one of the five elements of the world ( Earth,Water,Fire,Air and Space). He is the mightiest of all.
Vaayu gave a boon to Kunthi by which she begot a son bheema.
Hanumaan, the famous monkey-god in Raamaayanam also was the sun of Vaayu, born to Kesari's wife Anjana as an element of Lord shiva.
Vaayu is the deity of the asthra "Vaayavya" which shakes off the enemies like a wind blowing off dry leaves.
There was a sage too by this name Vaayu. He was mentioned in shaanthi oarva as one among the sages that were with bheeshma during his last moments.