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.
grappas grapes grippes gorps grips craps crappies crapes groups gripes gropes carapace croppies groupies corps carps crops cripes croups carpus corpse corpus creeps crepes kreeps croupes
grappa crappie crappy grape grapey grapy grippe grippy