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.
numbness nimbyness nominees numinous pneumonias gnomons
numbness dumbness chumminess umbones ambones riminess nimbyness liminess lameness gumminess gaminess gameness commonness gemminess meanness humanness sameness homeyness hamminess hambones foaminess loaminess combines roominess seaminess dimness hominess demoness tameness womanness yumminess