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.
coprah copra copperah coppra coper cooper copier copper coppery coopery capoeira coappear caper capper cupper cuppier goopier kouprey
coprah para pariah prao prau pray proa copperah coppra copra opera spray supra whipray
cop coop copay cope copy coup coupe cowpea cowpie coypou coypu scop scope