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.
sprout spurt sport spirt sprit sprat spirit sporty sprite seaport support sparoid spiroid sporoid separate superroad superette suppurate sparid spored spared spired spread speared speered speired spiered spoored spurred supered sparred superadd
sprout parrot parroty pierrot proud pruta taproot typewrote uproot
sapor spiraea supra spurrey spry sopor spar spare sparrow sparry sapour spirea spire spiry spoor spore spray spree sprue spur spurry osprey