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.
spire spirea spiraea spore spare sprue spier spiry speir spree sapphire spur sappier seepier soapier soupier soppier spry spar spurrey spear spoor speer sapor sopor super supra spray sapour sapper sipper soaper sparry spurry supper sparrow zappier zippier
spire pyre copier roupier soapier sappier soupier pipier repair pappier pare speir spiry loppier spree nappier kouprey zappier lippier diapir gappier dopier cuppier tippier goopier weepier hoppier chippier hippier happier pure nippier prey pore sapphire soppier seepier spare rapier ropier peppier spirea spier spore mopier pair sprue quippier zippier loopier dippier pere tapir pier typier guipure whippier pree choppier