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.
grittier gritter grottier critter groutier garotter garter grater crittur gridder grouter greeter greater grodier courtier criteria greedier garroter quartier cowriter carrotier curter crater carter grader krater curdier guarder quarter courter cruddier carder corder cruder
ruttier prettier grottier frettier brattier rattier grittier gritter quartier dirtier portiere ratter ritter fritter heartier trotter fretter courtier chertier critter wartier fruitier troutier garotter partier tartier artier carrotier rootier frotteur groutier purtier rotter reutter shirtier
gritty grit griot grotto grotty