Firstly: Washing for the Disbeliever Once He is a Believer
It is mustahabb for the disbeliever to wash once they have accepted Islam.  Some scholars have viewed it as obligatory if there took place something that necessitates it during his disbelief. This is the position of the majority: Hanafis, the most common opinion among Malikis, and the position of Shafi`is.
Secondly: Washing from a Disappearance of Reason
It is mustahabb  Ibn Qudamah and others have quoted consensus that it is not obligatory to wash for the one who wakes up from losing consciousness without confirming janabah. to wash for one who has woken from losing consciousness without confirming janabah or menstruation. This has been explicitly mentioned by the Shafi`is, Hanbalis, and it is the choice of al-Shawkani, Ibn Baz, and Ibn `Uthaymin.
Thirdly: Washing for Jumu`ah
Fourthly: Washing for Eid
Fifthly: Washing after Washing the Dead
Sixthly: Washing for Ihram
Seventhly: Washing Upon Entering Mecca
Eighthly: Washing for `Arafah
The latter will be thoroughly discussed in its respective book and chapter.