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.
cowpat coapt coopt copout caput coped capita capote cooped copied copped couped
cowpat pat pate paty peat bowpot pupate repeat spait spat spate wept chapati chappati
cowpie cowpea cop coop copay cope copy coup coupe coypou coypu scop scope