This link: http://db.ewi.utwente.nl/Publications/PaperStore/db-utwente-0000003696.pdf was a complicated, boring but comprehensive explanation. of monadic terminology used in programming... but it's now gone.

In Haskell, u is called return, and m is called combinator, or 'join'.

Haskell books mention List as an example of a monad, and have a rather special interpretation of State Machine Monad.

Another example of a monad is Google's map/reduce.