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.
hefty heft haft haffet haffit
hefty lefty eft wifty tufty befit fifty heft left lofty naivety nifty safety softy defat deft refit weft reft shifty