I've taken a list of English words, and examined each of them to see what they sound like (using the PHP metaphone function). This page lists the most common metaphone codes, along with their words. You can also search for a word of your own, and see which words sound similar - and which ones rhyme, and which ones alliterate.
spays spas spaes spacy sepias sepoys spacey sops sups saps sips spaz spicy spazz spues spews sipes seeps space soups supes spies soaps speise speiss spicey spouse suppose
pays copays spays repays pas nappas cuppas papas kapas paps kappas lipase pase huppahs capias pupas sepias spacy spas dopas teapoys tepoys chuppahs repass pass bypass poppas spaes sepoys pias papaws papacy napas opahs cowpeas pacy koppas pawpaws paws peas nipas tapas tepas upas chuppas