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.
critter gritter crittur grittier cowriter criteria crater carter curter curdier courter cruddier grottier garotter courtier carrotier grater cruder carder corder krater garter greater quarter grodier grouter greeter gridder crowder creator curator corridor creature garroter greedier groutier quartier grader guarder
fritter critter gritter ritter brattier triter cowriter prettier ratter grittier crittur reutter garotter rotter bruiter rioter writer fretter frettier frotteur fruitier fruiter grottier rattier rewriter ruttier trotter