Sunni (80%) and Shi'ite/Shi'a denominations, plus some small ones.
Sufism is a Mystic school of thought that includes philosophers and muslims. Most sufism embraces the Quran and most of Shi'a and Sunni Islam's beliefs. Sufis believe that their teachings are the essence of every religion, and indeed of the evolution of humanity as a whole. The central concept in Sufism is "love".
The Hashshashin (also Hashishim), or Assassins were a religious sect (Nizaris) of Islam with a militant basis, thought to be active in the 8th through 14th (?) centuries as a group of brigands on the medieval Afghanistan Silk Road. Their own name for the sect was ad-dawa al-jadida which means the new doctrine and they called themselves fedayeen from the Arabic fida'i which means one who is ready to sacrifice his life for the cause. The name Hashshashin was given to them by their Muslim enemies. The group was the first to transform the act of murder into a system and an ideology directed against Muslim rulers that they saw as unpious usurpers... Although known as early as the 8th century, the foundation of the Assassins is usually marked as 1090 when Hassan I Sabbah established his stronghold in the mountains south of the Caspian Sea at Alamut. A Yemeni emigrant and an Ismaili Shiite, Hasan set the aim of the Assassins to destroy the power of the Abbasid Caliphate by murdering its most powerful members. http://en.wikipedia.org/wiki/Hashshashin
Wahhabism is a form of Islam founded by Muhammad ibn Abd al Wahhab (1703 - 1792). It is a fundamentalist (Fundamentalism) movement of the Sunni form of Islam and has become an object of surging interest because it is the major sect of the government and society of oil-rich Saudi Arabia, and claimed to be the sect of Saudi Arabia-raised Osama Bin Laden. http://en.wikipedia.org/wiki/Wahhabism http://webseitz.fluxent.com/images/muslimPopulation.JPG
Population by country http://www.iiie.net/Intl/PopStats.html