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.
sprit spirit sprite sprat spurt spirt sport sprout sparid sporty sparoid support seaport spiroid sporoid separate superette suppurate spared spored spread spired sparred speered speired spiered spoored spurred supered speared superadd superroad
sprit parity deport support sprite sprat spirt periti pert port prat purity part apart yperite aport cuprite rapport report seaport spirit sport pyrite spurt depart typewrite
spar spiry aspire spurry spur spry sprue spree spray spore spirea spare spire spiraea spier speir sparry sparrow spurrey supra osprey