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.
peppy puppy pappy poppy pep peep pepo pipy poppa pappi pup pap pip pop papa pipe poop pope pupa pupu
peppy gappy choppy whippy tippy dippy zappy sepoy sappy repay poppy happy heapy hippy hoppy cuppy buppy quippy repp chippy weepy tepoy zippy soppy seepy puppy guppy pipy pappy nippy nappy loppy lippy yuppy
peppy pep pappi pappy peep pepo poppa poppy puppy repp