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.
sweater sweatier swatter sweeter seawater swotter
sweater waiter water watery watter wetter wheatear whetter awaiter seawater swatter sweatier sweeter dewater tweeter
sweat sweaty swat sweet sweetie