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.
loupen lupin lippen lupine lapin lipin
loupen pen youpon shippen cheapen deepen ripen rappen open lupin lippen kippen keppen coupon copen jupon happen peon pein peen pean reopen spean upon shapen yaupon yupon
loup loupe lop clop slope slop plop gloppy glop flop floppy elope loppy lope loopy loop sloppy