thursday or Vir Var is dedicated to Shirdi Sai baba in the north, and Murugan, as Shiva's son kartikeya is known, in the south. Sai baba has many bhajans dedicated to him. In many parts, the day is also special to Vaishnavites who pray to Vishnu, and to even Hanuman in some places.
friday or Shukra Var is dedicated to all forms of goddesses, including lakshmi, the goddess of wealth and prosperity. Many Mahalaxmi mantras exist. friday is also considered an auspicious day in the south, for which no almanac need be consulted to begin a new venture.
saturday or Shani Var is dedicated to none less than Saturn, the planet. Various Shani Bhagwan stotra are recited to appease the god said to be extremely strict about dishing out punishments on the basis of one's karma. On this day, even Hanuman is revered, because of his beneficial powers against Saturn's male factory effects. sunday belongs to another planet, the planet we see every day and which sustains us namely, Surya, the sun god.