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.
harasser hoarser horsier
crasser harasser tressier dressier prissier praiser grosser greaser raiser raser reissuer brasier brassier eraser hoarser caresser coarser creaser creasier crosser cuirassier grassier greasier parser presser dresser drossier trusser
harass haars hairs hares harissa hears hearsay hearse hoars hoarse horas