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.
cowpies copies cowpeas copes coupes cops copious koppies coppice kewpies coops coups copse capes capias coypus copays coypous guppies caps cups kops capiz capos gapes gawps goops kepis cuppas koppas
cowpies kewpies tawpies pies yippies cheapies wipes weepies puppies poppies pipes pappies nappies koppies cowpeas copies hippies buppies spies guppies whoopies chappies chippies yuppies pes pis