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.
spired speired spiered spread spared spored spoored spiroid supered speered sparred speared spurred spirt sparid sprite spirit sparoid sporoid zippered separate superadd spurt sprit sprat sport superette superroad suppurate sporty sprout seaport support
paired speired repaired spired purred supered peppered spoored loppered parred peered speered sparred papered chippered diapered repoured rapiered reappeared lipread lappered copyread coopered spiered pored spread poured spared zippered paupered spored pried appeared preed pureed speared coappeared spurred tapered parried pared lippered coppered capered vapoured vapored kippered choppered
spiraea spiry spire spirea sprue aspire spree spurry spray spur spry sparrow spore sparry spare spar spurrey spier supra speir osprey