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.
spill spail spall speil spell spiel spile spoil sappily soapily sepal spale speel splay spool supple supply
pill spill pile pial pall peppily repoll roupily spall soapily spell spile pily spiel spoil uppile pili poll speil appall pull happily huipil lapilli loopily nippily papilla pupil ropily sappily spail pail dopily choppily