An excellent book for non-Muslims explaining various aspects of Islam.
Author: Pete Seda
Publisher: Islamic Propagation Office in Rabwah
Source: http://www.islamhouse.com/p/1301
A small treatise concern knowledge & scholars, its importance & merits.
Author: Abdul Aziz bin Abdullah bin Baz
Publisher: http://www.al-hidaayah.co.uk - Al-Hidaayah Publishing and Distribution Website
Source: http://www.islamhouse.com/p/1257
A refutation against those who deny the appearance of Mahdi, the coming of Dajjaal, and the descent of the Messiah at the end of time.
Author: Hammoud Ibn Abdullah Ibn Hammoud At-Tuwayjri
Translators: Abdul Qaadir Abdul Khaaliq
Discover Islam: A brief book that guides a person towards Islam, Islam is the religion and way of life of about one Fifth of the world's population. Muslims are of diverse nationalities, cultures and races, but their Religion teaches that all humanity is essentially equal. It guides them to the Straight Path.
Publisher: Ministry of Islamic Affairs, Endowments, Da‘wah and Guidance
The best explanatory translation of the Qur'aan by Muhammad Muhsin Khan and Taqi-ud-Deen Hilaali.
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/1237
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.