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.
freemen firemen foremen freeman fireman foramen foreman ferrymen firman fermion ferryman foramina vermin vermian
freemen firemen foremen freeman germen crewmen mermen premen wiremen choremen