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.
spry spiry spray spurry sparry spur spar spurrey sprue spare sapor sopor spree spore spire spoor super spear supra speir speer spier supper sapour sapper soaper sipper spirea soupier sparrow spiraea sappier seepier soapier soppier sapphire