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.
spree spire spare speer spore sprue spirea spiraea spur spurrey spar spry sapphire speir sopor spoor spiry spray spear sapor supra spier super sapper soaper spurry sparry sipper supper sapour sappier seepier soapier soppier soupier sparrow
pree spree pyre spore spire speer spare rapparee kouprey guipure pare puree pure prey pore pere peer sprue