Recs.
Updated
All told, a monad in X is just a monoid in the category of endofunctors of X, with product × replaced by composition of endofunctors and unit set by the identity endofunctor.
Specs
Pros
Pro Seriously Though, Category Theory is Cool
Even though this isn't a good explanation for someone who has never encountered these terms, understanding enough category theory to have it make sense will make you a better programmer.
It's often easier to work from programming towards math. So read about the category design pattern and go from there. There's another good article on the same site talking about functors as a pattern. When you're ready to have your mind baked a bit more check out how objects are comonads. (disclaimer: this is not my blog, it's just awesome)
So think of monads like programmable semi-colons now, but always have an eye towards gaining a deeper understanding.