One of the most authentic book of Duas and Munajat, written by Imam Ali ibne Hussain Zain ul Abideen (as) although not all of the duas made to us, however the original book was given by Imam Muhammad al-Baqar to his Shi'as and mostly it is the most authentic book after al-Qur'an.
The book itself with Urdu translation is here for download:
Duas of Sahifa -e- Sajjadia in Urdu mp3 format to are available to be downloaded here so that you can listen to them while travelling or in leisure time (on any mp3 player or you can burn to audio CDs):
Nehaj-ul-Balagha (The peak of eloquence), a very authentic collection of Sermons, Letters and sayings of Imam Ali (as), which was compiled by Sayyid-e-Razi in the 4th Hijra, it is considered one of the most authentic collection of Imam Ali's sermons and letters - accepted by both Shi'a and the Sunni schools of thought. It is available to download as a book here:
Another collection of Sermons, Letters and Sayings of Imam Ali (as) known as Nehj-ul-Israr, this one is compiled by Sayyid Ghulam Husain Raza. This compilation is not as authentic as Nehj-ul-Balagha since this one contains a bigger collection of Sermons and Letters collected from various sources, hence the purpose was collection and not thorough research on authenticity, but regardless of that it is a brilliant effort. Available to be downloaded: