The original monad papers, by Philip Wadler. Accept no substitutes.

http://homepages.inf.ed.ac.uk/wadler/topics/monads.html

http://homepages.inf.ed.ac.uk/wadler/

Alternatively, if you really are allergic to LaTeX, or beards, the recently Oscared sigfpe’s “You Could Have Invented Monads! (And Maybe You Already Have.)”

http://blog.sigfpe.com/2006/08/you-could-have-invented-monad...

There are no other monad tutorials. Just forget about them.