The Nine Conditions of the Testimony of Faith.
Author: Jamaal Zarabozo
Publisher: Al-Basheer Magazine
Source: http://www.islamhouse.com/p/1371
A great book which explains the real beauty of Islam, by Dr Naji Ibrahim Arfaj.
Author: Naji Ibrahim al-Arfaj
Publisher: http://www.abctruth.net - ABC Truth Website
A discussion of the 'pillars' of Eemaan and the factors which invalidate ISlam and remove a person from its fold.
Author: Abdul Aziz bin Abdullah bin Baz
Source: http://www.islamhouse.com/p/1227
The Virtues of Allah’s sacred month of Muharram and Fasting on Aashooraa.
Author: Muhammad Salih Al-Munajjid
Publisher: http://www.islamqa.com - Islam : Question & Answer Website
Source: http://www.islamhouse.com/p/1343
A wonderful booklet mentions the predictions about the Prophet Muhammed (Peace be upon him) in Psalm, Old Testament and New Testament. It also discusses some other issues.
Publisher: http://www.rasoulallah.net - Website of Rasoulullah (peace be upon him)
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.