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.
guppy cuppy gappy quippy gapy cuppa goopy quippu cup gap copy coup gape gawp goop quip
buppy guppy yuppy puppy cuppy cuppa chuppa quippy chippy poppy tippy happy zippy hippy soupy hoppy sappy gappy pipy loppy lippy soppy nappy zappy nippy dippy pappy whippy peppy choppy roupy