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.
sleepy sleep salep slippy sloppy salp slap slip slop salpa slipe sloop slope slype saloop salpae
sleepy bleep kelep kelpy sleep
sale seel seely slew sloe slue sole solei isle