on being asked by a fellow Awo, I compiled this list of recommended books. I've read all of these (some better then others). This is by no means comprehensive, and I suspect I've overlooked some. Enjoy!
Marcos Ifalola Sanchez
• Olodumare: God in Yoruba Belief - E. Bolaji Idowu
• Fundamentals of the Yoruba Religion (Orisa Worship) - Chief Fama
• Yoruba Beliefs and Sacrificial Rites- J. Omósadé Awólàlú
• Practitioner's Handbook for the IFA Professional - Chief FAMA (Àìná Adéwálé-Somadhi) (Awos only)
• Odun Ifa. Ifa Festival - Emanuel Abosede (mainly for Awos)
• IFA: The Key to it's Understanding - Fasina Falade (mainly for Awos)
• Ifa: An Exposition of Ifa Literary Corpus - Wande Abimbola (mainly for Awos)
• IFA Divination Poetry - Wande Abimbola (mainly for Awos)
• Yoruba Oral Tradition - Wande Abimbola
• Ifa Divination: Communication Between Gods and Men in West Africa - William Bascom
• Ifa: A Complete Divination - Ayo Salami (mainly for Awos)
• Iyere Ifa (Tonal Poetry, the Voice of Ifa) An Exposition of Yoruba Divinational Chants - Chief Ifayemi Elebuibon
• The Healing Power of Sacrifice - Chief Ifayemi Elebuibon (mainly for Awos)
• Ifism: The Complete Work of Orunmila - C. OsamaroIbie (mainly for Awos)
• Iwe Odu Ifa - Chief Ifayemi Awopeju Bogunmbe (for Awos)
• A recitation of Ifa, oracle of the Yoruba - Judith Illsley Gleason, Awotunde Aworinde (mainly for Awos)
• Beads, Body, and Soul: Art & Light in the Yoruba Universe - Henry Drewal, an AMAZING book on the significance of beads and much of the art related to Ifa/Orisha.
• Odu Ifa: The Ethical Teachings - Maulana Karenga• Ewe: O uso das plantas na sociedade ioruba - Pierre Verger
• Orin Orisa: Songs for Selected Heads - John Mason
• Beads, Body, and Soul: Art and Light in the Yoruba Universe - Henry Drewal and John Mason
Idana fun orisa: Cooking for selected heads - John Mason and Gary Edwards
• Voodoo: Mounted by the Gods - Alberto Venzago (a view of "Fa" in benin)
• 1000+(African) Òrìsà Yorùbá Names - Chief Fama
• Fama's Ede Awo (Orisa Yoruba Dictionary) - Chief Fama
• Yoruba-English/English-Yoruba Modern Practical Dictionary - Kayode J. Fakinlede
•Je K`A So Yoruba (Yale Language Series) - Antonia Yetunde Folarin Schleicher
•Yoruba Proverbs - Oyekan Owomoyela
• I HATE recommending anything that makes Niemark money, but this book had good translations: The Sacred IFA Oracle - Afolabi A. Epega, Philip John Neimark (mainly for Awos)