Work in Progress.... Please send in contributions!
The first book on my list is the one that go me started...
Clive Barker's Weaveworld.
In which you will read how the prized racing pigeon, #33,
escapes from it's coop and thus begins one man's journey
into the Weaveworld.
Dante's Divine Comedy is composed in 3 parts (Hell, Purgatory, Heaven) and each part is composed of 33 Cantos.
Philip K. Dick's book the Transmigration of Timothy Archer features a significant mention of a 33rd Canto of the Divine Comedy. (I have to re-research this to mark which part the canto is from)