'Gerusalemme liberata' works so well, for me, because it draws on very everyday translation practices and shifts to achieve its purpose - it plays with cognates, with word-for-word translation, with collocation, with rhyme, with ambiguity and misunderstanding. And it only cheats sometimes.
For more of this sort of thing, see the 'Mistraduzioni' in Almansi's marvellous book Maramao (Longanesi, 1989) (but be warned, those of a prudish disposition may wish to steer clear). My favourite part is the dedication:
A David O’C., studente di primo anno a University College, Dublino, che gloriosamente mistradusse le prime due parole degli Indifferenti di Alberto Moravia, “Entrò Carla”, con “He entered Carla”.
[For David O'C., first-year student at University of College, Dublin, who gloriously mistranslated the first two words of Alberto Moravia's Gli Indifferenti, “Entrò Carla” [Carla came in] as "He entered Carla".Photo from http://www.aforismario.it/guido-almansi.htm with thanks.