This day is also of utmost importance for the followers of the Nath Sampradaya because Guru Dattatreya is the Param Guru of the Nath Sampradaya and Navnaths or the Nine Universal Masters. Most readers will surely have noticed the numerous Shabar Mantras posted on this site, which have originated from the Navnaths or those belonging to the lineage of the Nath Sampradaya.
There are numerous ancient scriptures dedicated to the orign and nature of Dattatreya. Without going into the merits and de-merits of these scriptures, it is evident that the Navnaths, worshipped Guru Dattatreaya as the Param or Utlimate Guru or Teacher, the Guru of All Gurus, the Ever-Existent God.
They visualized Dattatreya as the One who transcends or the One who is beyond the three Gunas, Satvik, Rajsik and Tamsik, symbolized by Brahma, Vishnu and Shiva.
For the practitioners of Mantra Vidya, this day is most auspicious for commencing any kind of Satvik Siddhi Sadhana, especially those Sadhanas related to the gaining of Paranormal Occult Powers. For the lay-person, the remembrance of Guru Dattatreya can prove to be immensely beneficial and helpful in eradicating mental defects and disturbances, including those, which have originated from sins committed in this or the previous lives.
In mu opinion, and this is derived from discussions with some people belonging to the Nath Parampara, there is no need to specially worship Guru Dattatreya, he is always there to help and guide good people or those persons who wish to leave behind a turbulent past and overcome the bad Karma of their present or previous lives and move ahead in life.
A wide range of Mantras and Prayers dedicated to Guru Dattatreya can be seen here - Dattatreya Mantras