Nice and simple Puntuado con 5 de 5 estrellas
It does what is described, does very nice, clear and with taste.
But actually we don't need addon itself. It is enough to add this site to search machine, give it short name (for instance - t) and adding @t and space before site where you are in url bar will give you all that you need.
Moreover, if you'll bookmark this site as http://www.tawdis.net/ingles.html?lang=en%s (add "%s" to address) and give it short name (let say, t) you can type t with space before address of site where you are - and it will give you what you need :)
Excellent site! Thanks!