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.
quack quacky quick quake quaky quickie quag guck guaco quagga quokka guaiac quaggy cuckoo cuke cock kaka cook caky caca kick gawk kaki coke coky keck cake
quack jacky quaky lack quacky guck quake duck tuck tack wacke wrack wacky suck rack whacko puck chuck knack shack lucky shuck muck yuck quick guaco jack sucky buck bucko luck hack huck fuck ducky wack tacky wacko sack back whack ruck whacky pucka chucky pack shacko mack yack mucky yucky
quack quacky qua quai quay aqua aquae guaco quag quagga quaggy quake quaky quick quickie squaw