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.
preps preops prepays perps props preppies prepuce priapus pyropes hyperopes hyperopias propose purpose porpoise
reps preps carps carpus corps corpus creeps crops herpes grips larrups perps fraps props sirups dorps drops tarps trips urps chirps sharps preops burps harps gorps raps arepas wraps rips repps repos kreeps reaps corpse crepes craps bewraps rewraps syrups drips hydrops traps turps warps chirrups sherpas
prep prepay preppie preppy perp preop prop