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.
posset psst poussette post posit posed pissed peseta pst poised postie passed piosity passade past pest pesty pseud paste pasty pasta piste pastie paused peised pesade posada pseudo passado
asset russet basset misset tasset cosset knesset gusset posset set seta dossed dissed sett messed moussed bossed reset reseat russety jessed mossed mussed peseta suet sassed misseat tossed coset chassed fessed hissed guessed cessed massed cussed disseat bussed keyset bassett beset pissed gassed missed kissed seat psst passed fussed sussed miseat biassed wissed roset yessed
posse pass popsie epos passe passee piss poesy pois poise poos pose posy poussie pows puss pussy apos pops popsy