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.
coast cost cast caste coset costa costae cosset casita cassata gast caseate coesite casette cassette cased caused cosied cuesta gaseity gooiest gust kist
boast oast roast coast toast roust host hasty nasty foist hast baste fast east boost taste sayst vast roost coset roset maist mayst most oust pasta pasty post joist tost wast wost yeast ghosty costa gast dost hoist bast past joust last vasty cast hosta doest beast feast haste cost ghost least posit lost mast moist moste caste ghast paste tasty toasty waist waste chaste yeasty
cos cosey ocas coxae cogs coax goas coys cows cosy coss cosie coos casa cays caws causey cause cassia case koas cocas coxa oaks okas