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.
copula copulae cupula cupulae copal couple cupola cupule cupel
pula cupula papula copula pul plea splay pule pepla puli papule hoopla cupule play byplay cupulae papulae pull peepul copulae replay cupola whoopla
cop coop copay cope copy coup coupe cowpea cowpie coypou coypu scop scope