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.
crapes craps crappies grapes crepes cripes croupes crops corps carps croppies creepies carapace carpus gropes gripes corpse croups corpus creeps grappas grippes croupous groupies gorps grips groups kreeps
rapes serapes trapes grapes crapes sarapes drapes tropes pyropes preppies liriopes gropes gripes ropes traps rupees creepies crappies rappees ripes croppies crepes carps hyperopes sharpies cripes warps croupes fraps tripes herpes harps harpies raps priapus frappes tarps groupies troupes rewraps grippes craps towropes reaps drupes wraps bewraps sharps
crap crappie crappy crape crepy scrapie cripe scrap carp carpi crepe crepey crop grapey grappa grapy croppie scrape grape scrappy