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.
retirer roturier
retirer litterer chatterer utterer titterer stirrer trier potterer pewterer patterer mutterer miterer maturer loiterer letterer direr caterer fetterer bitterer batterer truer putterer starer storer totterer waterer shatterer
retire retiree retore retro retry