Light Within Me - A collection of Essays on I'rfan and Spirituality featuring writings of Ayatullah Murtadha Mutahhari, Allamah Muhammad Hussein Tabataba'i, and Ayatullah Ruh'ullah Khomeini (external site)

Lantern of the Path - A collection of spiritual narrations from the sixth Imam, Imam Ja'far as-Sadiq (as) touching on a number of different topics. (external site)

Self Building - By Ayatullah Ibrahim Amini (external site)

Forty Hadith - By Ayatullah Ruhullah Khomeini (external site)

Ethics and Spiritual Growth - By Sayyid Mujtaba Musavi Lari (external site)

Adab as-Salat: The Disciplines of the Prayer - By Ayatullah Ruh'ullah Khomeini (external site)

Salat al-Lail - A description of how to perform the recommended night prayer and of the benefits of this prayer.  From "Weapon of the Believers" by Allamah Muhammad Baqir Majlisi (external site)

Prayer as a Journey Toward God

On Islam and Religious Pluralism

On the Islamic Conception of Freedom

Ramadan as a Means of Forging a Connection With God

Is God in Islam Distant and Impersonal?

The Bird Parliament (Mantiq at-Tair) by Farid ud-Din Attar (ca. 1120-1220 CE)

Masnavi-e-Ma'navi by Jalal ud-Din Rumi (1207-1273 CE)

On Ibn Sina (980-1037 CE)

Page on Ibn Sina from muslimphilosophy.com 

On Abu Hamid al-Ghazali (1058-1111 CE)

Page on works and life of Al-Ghazali

Translations of parts of Ih'ya fi i'lm ad-din (Revival of the Islamic Sciences), generally understood to be Al-Ghazali's most significant work.

Alchemy of Happiness (Kimiye-e-sa'adat), a summary of the main ideas of the Ih'ya

The Niche of Lights (Al-Mishkat al-Anwar)

On Shahab ad-Din Suhrawardi (1155-1191 CE)

Page on Suhrawardi from muslimphilosophy.com 

Page on Suhrawardi from Stanford Encyclopedia of Philosophy

On Ibn al-A'rabi (1165-1240 CE)

Ibn A'rabi Society - with information on Ibn al-A'rabi, a great Muslim thinker in 12th to 13th century Andalusia (now Spain).

Anqa Publishing - with more information about Ibn al-A'rabi.  

On Mulla Sadra (1571-1640 CE)

Sadra Islamic Philosophy Research Institute (Iran)

Another page on Mulla Sadra