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.
crupper cropper crapper crappier croupier carper creeper grouper crepier gripper grippier creepier griper groper corpora grapery grapier gripier
crupper cropper trippier trapper drippier syrupier preppier larruper grouper grippier gripper croupier crappier rapper crapper frippery wrapper roupier ripper reappear sirupier dripper dropper tripper trouper
crappie crappy croppie croup croupe croupy