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.
spader spider spatter speeder spidery spudder speedier scepter spitter spotter spouter sputter septaria spottier sputtery sceptre
spader padder padre padri pater powder powdery rapider repeater speeder speedier spider spidery spudder tapadera tapadero
spade spado spaed spait spat spate sped spode spud