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.
knotter knottier knitter noter nutter natter netter nittier nuttier nattier nettier gnattier niter neater nodder neuter nitery notary niterie kneader nitre nuder nature needer nutria needier
hotter potter knotter lotter jotter totter rotter cotter otter dotter litter toter hootier bitter fitter dotier netter nittier batter mutter phatter getter butter hooter loiter bootery gutter fattier router coater putter guttier battery pottery mooter cattery rootier cutter looter patter shutter shooter shatter chattier chatter whitter wetter utter tottery tetter tatter dottier sootier titter fetter setter footier battier ratter voter cattier footer pettier hitter outer zootier couter nuttier nettier matter noter vetter rattier reutter sitter knitter ritter ruttier pouter jitter nutter buttery powter hatter gnattier guttery cooter jittery fatter quitter petter knottier bittier letter littery lottery quoter oater cottier better puttier jettier goiter nattier rioter cottar latter ottar pottier souter mattery natter tater doter tattier titer tooter rooter boater touter watter whetter wittier chattery chitter shittier shouter yatter