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.
niacins niceness noisiness nascence nascency nosiness nuisance naissance nescience newsiness
niacins cines diazins ricinus cions sains scions acinus basins fascines ficins fusains leucines leucins mucins oscines piscinas ricins sasins hyoscines