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.
casitas casts cassatas castes coasts caestus cuestas casettes costs coesites gasts caseates cassettes gaseities cosets custos cossets gusts kists quaysides guests quests gussets gustoes keysets
casitas sits zoisites cestas resites pesetas missuits cuestas cassatas jesuits hostas hessites vistas visits fiestas vestas eustasy suits stoas stays situs sites coesites lawsuits pastas posits resits siestas diastase
casita cast casette caste coast