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.
sprat spirt spurt sprit sport separate spirit sprout sporty spread sprite suppurate seaport support superadd superette superroad sparid spired spored spared spiered sparoid speered speired spiroid sporoid spoored spurred supered sparred speared
prat sprat depurate depart support sprit spirt apart sport separate pert pirate port prate part seaport apparat biopirate cooperate operate rapport reoperate report aport spurt suppurate deport uprate
spray spirea supra spurrey spur spry sprue spree spore spiry spire spar spiraea spear sparry sparrow spare spurry osprey