The testimony of "Laa ilaaha ill-Allah", its meaning, prerequisites, conditions, and fruits.
Author: Saleh Bin Fawzaan al-Fawzaan
Publisher: http://www.islammessage.com - Islam Message House Website
Source: http://www.islamhouse.com/p/1223
This book gives a clear explanation of the Muslim sound Creed which is the core of the religion of Islam, as the belief in Tawhid (monotheism) is the purpose for which Allah created both mankind and jinn, and thus, those whoes belief in Tawhid is corrupt, are not considered Muslims.
Author: Saleh Bin Fawzaan al-Fawzaan
This is a brief book which explains the meanings and the definitions of the miracle. It also takes a look at some of the scientific facts mentioned in the Quran which modern scientists, Muslim and non-Muslim alike, affirm as true.
Author: Ahmed Deedat
The best explanatory translation of the Qur'aan by Muhammad Muhsin Khan and Taqi-ud-Deen Hilaali, with verse by verse recitation embedded into the file
Translators: Muhammad Muhsin Khan - Taqi-ud-Deen Hilaali
Publisher: http://www.qurancomplex.org - King Fahd Complex For Printing The Holy Quran Website
Source: http://www.islamhouse.com/p/1241
Introduction to history of polytheism and monotheism: Allah (glory be to him) created all people as Muslims and monotheists but devils came to them and changed and distorted their religion. Allah said in a qudsi hadith, “I created all my slaves as haneefs (monotheists), but the devils came to them, made them deviate from their religion, forbade them that which I had permitted to them, and commanded them to join partners with me for which I has given no authority.” As soon as people commit a type of polytheism, Allah sends his prophets to call them to the suitable type of monotheism.
Author: Ameen Al-Ansaari
Publisher: A website Knowing Allah : http://knowingallah.com
This is a useful book although it is small. It contains some technical terms for da'wah in English. No doubt all scholars and callers to Islam in English are in much need to something like that to conveys the right message of Islam to all those speak English.