A most rewarding and fulfilling part of a Muslim's worship are those blessed moments that he spends praying in the depth of the night, privately addressing his Great Lord, sincerely glorifying Him, humbly imploring Him - beseeching His forgiveness and asking Him for favors. The voluntary "night prayer", or qiyaam, is indispensable for a person's moral, spiritual, and physical welfare. Yet, it is greatly misunderstood and largely neglected by most Muslims
Author: Muhammad Naasiruddeen al-Albaanee
Translators: Abu Maryam Ismaeel Alarcon
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
These are three good books for learning Arabic Language for the non-native speakers. But we should pay your attention that they are for who has slightly good knowledge about Arabic and how to pronounce it. We don't claim that you can consider them as an alternative to a teacher but they are good step for who wants to be excellent at Arabic. With these books, there is an Arabic-English glossary confined to the words mentioned in these books, and the author shows in its introduction how to find any word.
A nice discussion of some important points needed by those callling to Islam
Source: http://www.islamhouse.com/p/1243
Brief guide concerning the fundamentals of Islam.
Author: Naasir Bin Abdulkarim al-Aql
Source: http://www.islamhouse.com/p/1295
An interesting book contains more than eighty means of da'wah in different fields of our life such as da'wah at home, masjed, school and work in addition to various means of da'wah. These books teach us that we should not confine da'wah to masjed but it should far exceed it to include all life's fields. Based on these means of da'wah, we can direct da'wah to everyone by easy ways. We should know that da'wah is a responsibility of every Muslim, the issue which encourages us to use these means efficiently.