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.
retreat retread retort reiterate retired retried rehydrate reuttered retard redried ritard redroot
retreat treat tret citrate titrate street strati strata strait outread retread outrate nitrate treaty tread trait whittret
redrew retear retire retiree retore retro retry ureter