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.
cupule cupulae cupula couple copulae cupel copula cupola copal
cupule pule papule pul maple apple nipple fipple papulae copula cupulae cupula popple peepul pull spale supple dapple dipole tipple uppile papula pole hopple maypole plie plew plea pile pele pale puli pula people copulae couple ripple spile zeppole diploe duple topple wheeple
cup coup coupe cuppa cuppy scup