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.
billowier blowier bellower blower
blowier billowier willowier lower plower shallower wallower glower willower hollower slower hallower follower callower mellower flower flawier blower bellower lowery flowery sallower yellower