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.
copal copula couple copulae cupel cupola cupula cupule keypal cupulae
nopal opal copal pal people typal appal tapalo keypal spale hoopla sepal appeal pupal appall peal pial papal pipal pawl repeal paly spail pall spall pale tepal pail whoopla
copay cop coop cope copy coup coupe cowpea cowpie coypou coypu scop scope