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.
unseal unsell unusual uneasily unusually
unseal mainsail unsell ainsell hansel conceal counsel gunsel nasal moonsail mensal nonnasal censual sensual densely tensely tinsel unusual