One of the most detailed books describing the rulings of Hajj, Umrah, and visiting the Masjid of the Prophet (peace be upon him).
Author: Sayid Sabiq
Source: http://www.islamhouse.com/p/1395
Fortress of the Muslim, Invocations from the Quran and Sunnah: is a very beautiful booklet consists of many authentic Dua's (supplications) for a Muslim to supplicate on a daily basis and on special occasions.
Author: Saeed Bin Ali Bin Wahf Al-Qahtani
The Muslim Nation today is experiencing a blessed awakening in all aspects of its affairs; one that has been aroused by the efforts of the Muslim youth. However, the astute observer of this awakening will find that there are many problems that hinder its progress; problems that have prompted some scholars, callers to Islam, and students of knowledge to lay down some guidelines that the youth of this blessed awakening should adhere to and follow.
Author: Muhammad ibn Saleh al-Othaimeen
Reveiwers: Muhammad AbdulRaoof
The universality of Islam is an undeniable fact, a characteristic peculiar to Islam, the Righteous Religion. Almighty Allah has assigned Muhammad Ben Abdullah as Prophet and Messenger to the entire mankind, revealing to him His Holy Book to serve as a means of guidance and a reminder to all humanity. It was the will of Almighty Allah to make the Islamic Message the seal of revealed messages, which thus gave form and substance to the Righteous Religion.
Author: Abdullah Bin Hadi Al-Qahtani
Reveiwers: Muhammad AbdulRaoof
Publisher: Islamic call and guidance centre in Abha: www.taweni.com
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