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.
ripest ripost riposte ropiest roupiest rapist repast rapeseed reposed reposit rapacity repassed
heppest cheapest ripest hippest pest deepest pst ripost zippiest psst loppiest post nappiest rapist zappiest pesty ropiest goopiest pesto lippiest dippiest pipiest soupiest roupiest hoppiest soapiest bypast chippiest papist quippiest loopiest seepiest repast pappiest mopiest cuppiest peppiest gappiest epeeist sappiest tippiest upset whippiest hippiest past happiest soppiest nippiest dopiest typeset typist weepiest typiest choppiest
ripes rapes rips ripsaw ropes rupees cripes gripes grippes grips drips tripes tripos trips