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.
gropes groupies groups gripes grapes grippes croupes grips crops gorps croppies croups cripes crepes crapes grappas crappies creepies croupous carps corps craps carpus corpse corpus creeps kreeps carapace
ropes tropes gropes pyropes liriopes towropes hyperopes rupees preops crappies troops creepies crepes rappees croppies corps props hydropsy preppies frappes herpes harpies drapes drops rapes troupes trapes tripes crapes sarapes gripes grapes grippes gorps groupies serapes roups dorps ripes drupes groups crops droops dropsy hydrops cripes croups croupes sharpies
grope crop croppie gorp grape grapey grappa grapy grip gripe gripey grippe grippy gripy group groupie