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.
opens openness opines
pens opens cheapens deepens shippens reopens copens happens lippens ripens jupons spins paeons peans japans lipins peens ripienos spense peons peins pons gipons coupons yapons spans youpons penes shippons repins lupins pippins sapiens weapons puns teopans pins taipans tiepins lapins pans paeans penis speans capons chopins yaupons kneepans yupons