As stated above, the different gods of the Hindu pantheon have different functions which you can call upon to get ahead in life. For example, Hindu's worship the elephant-headed Ganesha before beginning any religious, spiritual or worldly activity, as He is said to remove obstacles and ensures success. With her necklace of skulls and near permanently poked out tongue, Kali (the Dark Mother) is one of the more fearsome Hindu deity. This goddess, however, can provide devotees with a very loving and intimate bond, in spite of her fearful appearance. In this relationship, the worshipper becomes a child and Kali assumes the form of the ever-caring mother. I used to live with an American girl who worshipped Kali, and she faithfully wore a skull necklace wherever she went. Lord Vishwakarma is the architect's god and the presiding deity of all craftsmen. Son of Brahma, he is the divine draftsman of the whole universe, and the official builder of all the gods' palaces. Vishwakarma is also the designer of all the flying chariots of the gods, and all their weapons. If you are a craftsman perhaps you should consider praying to him every September 17 to gain some higher inspiration!
Ganesha: He is the son of Shiva and lord of obstacles, who goes by several names such as Ganapati, Vinayaka, Gajanana, Vighnaraja, Vakratunda etc. He is one of the most popular gods of the Hindu pantheon, who is invariably worshipped in all rituals before offerings are made to other deities. He enjoys this exalted position because he is considered the leader of the gods and the first among them. He has a rather unusual forms due to the circumstances related to his origin. He has an elephant head with a rather oversized human body, with four or more hands. He is considered god of knowledge and wisdom and often equated with Brihaspati or Bahmanspati, the teacher of gods, mentioned in the Vedas. There is a sect of Hinduism, called Ganapatya sect, in which he is worshipped as Brahman himself. He has numerous aspects, some pleasant and some fierce. Sometimes, he is shown in the company of his consorts, Riddhi and Siddhi and sometime in the company of Lakshmi as Lakshmi Ganapati. There are numerous temples built in his honor in various parts of India.
Shirdi Sai Baba appeared in India in the state of Maharashtra in the 19th century. He has millions of followers who consider him a Saint and an Avatar. Many people believe that he is one of a series - a triple Avatar: Shirdi Sai Baba, Sathya Sai Baba and (one yet to appear) Prema Sai Baba. There are many temples dedicated to Shirdi Sai Baba, mainly in Maharashtra but also all over the country. I personally believe, that Sai Baba can indeed be considered a God, and worship of Sai Baba can be substituted for any of the male Gods of the Hindu Pantheon (with the exception of the Goddesses and Ganapati). In fact, the chances of prayers to Sai Baba being answered, are possibly higher than prayers to one of the other human incarnations (this is because Sai Baba is still personally present in the Earth sphere, preparing for his next incarnation).
Devotion to God and the Gods of Hinduism is known as Bhakti. It is an entire realm of knowledge and practice unto itself, ranging from the childlike wonder of the unknown and the mysterious to the deep reverence which comes with understanding of esoteric interworkings of the three worlds. Hinduism views existence as composed of three worlds. The First World is the physical universe; the Second World is the subtle astral or mental plane of existence in which the devas, angels and spirits live; and the Third World is the spiritual universe of the Mahadevas, "great shining beings," our Hindu Gods. Hinduism is the harmonious working together of these three worlds.
Hanuman: Hanuman is one of the most popular gods of Hinduism today. He is the son of Vayu, born with the powers and blessings of Shiva. He played a vital role in the Ramayana, assisting Rama in finding Sita and fighting on his behalf with the demons of Ravana. He has the features of a monkey, with a strong human body and heart of gold. He is known for his exemplary devotion to Rama and Sita. He also served as an emblem for the Pandavas during the Mahabharata war. He is worshipped in numerous temples across India and elsewhere. Hanuman Chalisa is the most popular prayer of Hanuman which are sung in millions of Hindu households and temples to invoke Hanuman and seek his blessings.