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.
nifty nighty naivety night knifed knight naivete naughty nightie
nifty wifty shifty fifty rift tufty suavity softy sift safety lofty levity lefty cavity gift hefty shift lift
knife naif neif sniff sniffy unify