Nanam Dorje Dudjom is another of Guru Rinpoche's twenty-five disciples and his full biography can be read on the Treasury of Lives site.
There are also several references to him in books in English.
An exchange between he and Guru Rinpoche is included in Guru Rinpoche: His Life and Times. The full translation includes Nanam Dorje Dudjom requesting a prayer for the benefit of future generations and the 120 line prayer. The Nyingma tradition generally prescribes reciting this prayer in the afternoon as part of a daily cycle of prayers Guru Rinpoche gave to particular disciples. Details on this are included in Khenpo Ngagchung's A Guide to the Words of My Perfect Teacher.
In The Dark Red Amulet, Khenpo Palden Sherab, describes how he pointed a phurba at the Tsangpo River near Lhasa and stopped its flow through the power of Vajrakilaya.
Nanam Dorje Dudjom also appears in the 19th century Autobiography of Jamgon Kongtrul who relates how he requested a Vajrakilaya empowerment from his teacher. Before granting it, his teacher had a pure vision where he received the transmission directly from Nanam Dorje Dudjom and subsequently bestowed the empowerment on Jamgon Kongtrul.
There are many points in Tibetan history where he appears directly or in rebirths.
In Khenpo Tsewang Dongyal's biography of Dudjom Rinpoche, Light of Fearless Indestructible Wisdom, the story of his fourteenth century rebirth, Rigdzin Godem Chen relates how he discovered the Guru Rinpoche's treasure, the Gongpa Zangtal, a core text in the Northern Treasures lineage.
Khenpo Namdrol, in his book The Practice of Vajrakilaya, talks about how there are three terma transmissions of the Vajrakilaya teachings. One relates to King Trisong Detsen, one to Yeshe Tsogyal, and the other to Nanam Dorje Dudjom. The latter was rediscovered by his reincarnation, Lerab Lingpa. The Gur Khukma Vajrakilaya treasure discovered by the great 20th century master Khenpo Jigme Phuntsok also belongs to this same tradition. On a related note, In Dzogchen: Heart Essence of the Great Perfection, Nyoshul Khen Rinpoche identifies Sogyal Rinpoche as a reincarnation of Nanam Dorje Dudjom.
Dudjom Rinpoche also mentions him in The Nyingma School of Tibetan Buddhism, published by Wisdom Publications.
Lineages associated with him as well as other information are on the TBRC site.