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.
whetter wetter whitter wheatear watter whiter wittier whitier water waiter wedder weeder watery weedier watthour wader wider wadder widder woodier
fetter setter letter whetter getter better wetter tetter vetter petter netter gutter cattery lotter hitter tatter battery mutter quitter feater pettier peter hatter phatter vetoer cottier pottery jotter guttery fattier gnattier retear ratter matter nettier litter ruttier tattier shutter sheeter chitter chattier chatter whitter utter totter titter fatter dotter hetero tater putter deter knitter eater ritter guttier heater littery beater metier natter bittier buttery pewter neuter rattier jittery nittier reutter jitter fitter knottier nattier latter meteor quieter lottery patter batter potter cattier teeter meeter nutter butter watter hotter neater puttier battier sitter tottery jettier meter mattery pottier knotter bettor bitter rotter cotter cutter dieter seater dottier otter titer toter nuttier wittier chattery cheater shatter shittier yatter