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.
sayst cyst xyst xysti sassed siesta xystoi seaside cist zest
mayst sayst east boast beast gast last maist fast vasty pasta oast cyst feast roast xyst taste toast waist waste yeast pasty baste paste mast bast hast haste hasty cast caste vast coast least keyset nasty past ghast xysti tasty toasty wast chaste yeasty
says sass sassy saws seas soys naysays sasses sassies