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.
seas says sees sews sass saws seis sues cease zoeas sassy seise seesaw zas sos sis cess sous suss sows soys size sice syce saice sauce saucy seize sissy souse sycee cissy
keas leas peas seas zoeas teas toeas sheas yeas as es