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.
copulas copals couples cupolas cupules cupels capless gapless keypals
copulas puls splays replays peepuls papules cupules cupolas hooplas byplays appulse pulse pulls pulis pules pleas plays repulse whooplas
copula copulae copal couple cupula cupulae cupule scopula scopulae