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.
deafness daffiness deafens defines daphnes defence defense deviance defiance dauphines diaphones davens divans dovens devons diaphonies deveins divines daphnias dauphins deviancy tiffanies toughness diaphanous
deafness evenness toughness beefiness suaveness safeness rifeness puffiness naiveness liveness leafiness goofiness iffiness huffiness highness heaviness fanes fewness affines vainness finesse fines feyness miffiness nighness refines roughness savviness daffiness defines waviness