Sampradayas

The three sampradayas (sects) of Brahmins, especially in South India are the Smarta sampradaya, the Srivaishnava sampradaya and the Madhva sampradaya.

 Smartism

Smartism (or Smarta Sampradaya, Smarta Tradition, as it is termed in Sanskrit) is a liberal or nonsectarian denomination of the Hindu religion who accept all the major Hindu deities as forms of the one Brahman in contrast to Vaishnavism, for example. The term Smarta refers to adherents who follow the Vedas and Shastras.

Vaishnavism

One form of Vaishnavism is Madhwa ( Dwaita Sampradaya), and the other is Sri Vaishnava (vishista dwaita sampradaya). Madhwa Brahmins are mainly located in the Carnatic plains and some of them are seen in Andhra, Tamil Nadu and Kerala areas. They follow the preachings of Sri Madhwacharya, who born in South Canara district of Karnataka in 12th Century. He preached that God and atma (our soul ) is different as against the preachings of Sri Sankaracharya, who preached aham Brahmasmi (God and my soul are the same).
In south India Srivaishnava sampradayam was propagated by Srimad Ramanjuacharya Which has Given as bhakti marga by azhwar saints.

 Shaivism

Shaivism (sometimes called Shivaism) is a belief system where Lord Shiva is worshipped as the Supreme Lord. It is a derivative faith of the core Vedic tradition. Saiva sects contains many sub-sects, such as Rudrasaivas, Veerasiavas, Paramasaivas, etc. Ravana the Ruler of Lanka in the Hindu Epic Ramayana was a Devgan Brahmin Grand son of Sage Pulastya & So of Sage Visharva

Miscellaneous sects

There are additional sampradayas as well which are not as widely followed as the rest.
The Mahima Dharma or "Satya Mahima Alekha Dharma" was founded by the Brahmin Mukanda Das of present-day Orissa, popularly know by followers as Mahima Swami according to the Bhima Bhoi text. He was born in the last part of 18th century in Baudh ex-state as a son of Ananta Mishra. He was Brahmin by caste as mentioned in Mahima Vinod of Bhima Bhoi in Vol.11. This sampradaya is similar to Vaishnavism. Although the members of this sect do not worship Lord Vishnu as their Ishta-Deva, they believe that the Srimad Bhagavatam is sacred. The founder of this sect was a Vaishnavite before founding the new order.This sampradaya was founded in the latter part of the 18th century.
There is also the Avadhoot Panth, wherein Lord Dattatreya and his forms such as Narasimha Saraswati and Sai Baba of Shirdi are worshiped. Lord Dattatreya is worshiped by many as the Hindu trinity - Brahma, Vishnu and Shiva in one divine entity. Many even worship Dattatreya as an Avatar of Vishnu or of Shiva.