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.
unsaid unseat unused unissued unset
naysaid gainsaid unsaid gneissoid inside queenside quinsied monacid monoacid nonacid onside sinusoid downside
unsay uns unais unaus unease uneasy unsew