[hardwaresofton]

This is an excellent article, I think it explains the monad pretty simply, starting from an understanding of functors.

For those that are struggling with understanding (or feeling like you understand) monads, here are some articles like this one that I found very useful (note that the links are for haskell, but obviously, monads are a generally applicable concept).

A visual explanation of monads:

http://adit.io/posts/2013-04-17-functors,_applicatives,_and_...

The chapters on Functors, Applicatives, and Monoids that leads up to the chapter on monads (read the functors, applicatives, and monoids chapter first THEN the monad chatper and things will start to make sense):

http://learnyouahaskell.com/functors-applicative-functors-an...

[bvanslyke]

Personally it clicked for me after reading "You Could Have Invented Monads"[0] and LYAH (in order as you suggest).

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