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.
napas nappas naps knaps napes neaps nipas nappes nappies nips knops neeps
napas kapas tapas papas pas apse tapis gawps nipas opahs lapis kappas neaps gaps poppas paps spays spas maps capias saps tepas daps lapse soaps taps yaups shapes chuppahs cheapos chapes whaps upas dopas baps tapes jaups zaps knaps bypass repays reaps rapes lipase spaes capos capes cowpeas copays koppas apos napes naps gapes pays huppahs peas pias pase apps caps pass heaps laps japes leaps paws wraps apes repass sepias pawpaws pupas haps nappas cuppas whaups raps chaps cheaps papaws chuppas yaps waps yawps
napa nap knap nape nappa nappe nappie nappy neap nipa snap snappy