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.
whacko whack wacko whacky wack wacke wacky wake wauk weak wick wag wog wok
wacko whacko shacko jacky jack gecko hack pack wrack tack sicko taco guaco shack back wacky shako jocko bucko wacke quack quacky whack cacao wack tacky socko rack sack knack mako mack lack cuckoo whacky yack