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.
spail spile sepal spill spoil spiel speil spall spale sappily soapily speel spell splay spool supple supply
spail pail pal pawl keypal opal pial sepal roupily repeal pupal pale nippily peppily pall paly pili spall spiel spill dopily tepal uppile huipil pile pill ropily spile spoil spale speil appal papal peal pily soapily typal tapalo sappily pupil nopal pipal loopily copal happily appeal appall choppily