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.
cops copse coups coops copes copies copays coypus coupes kops caps cups cowpeas copious coypous cowpies capes capos goops capias cuppas koppas koppies coppice gaps keps kips capiz gapes gawps kapas keeps kepis quips
bops lops chops woops whoops sops pops poops ops oops knops mops loops fops kops goops cops coops hops hoops hyssops tops whops wops shops