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.
copen coupon capon keppen kippen
copen open reopen pen peon shapen happen cheapen keppen deepen pean peen pein kippen ripen spean lippen teopan loupen chopin rappen shippen
cope cop cape coop copay copy coup coupe cowpea cowpie coypou coypu scop scope