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.
hard hardy hared heard hoard hairdo haired herd hart hayride harried heart hired horde hearty heired horrid herried hurried hurt
bard card shard board fard hard heard hoard beard lard guard liard nard pard sard ward chard yard