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.
knaps naps knops napas napes neaps nappas nappes nappies nips neeps nipas kneepiece
knaps naps jaups capos caps gapes gaps gawps capes kapas laps leaps nips apes raps wraps soaps daps tapes taps whaps chapes cheapos shapes yaups paps apos japes neaps baps apse apps lapis lapse maps haps knops napes heaps napas papas rapes reaps saps zaps tapas tapis waps whaups chaps cheaps yaps yawps
knap nap knop napa nape nappa nappe nappie nappy neap snap snappy