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.
spiraeas spireas spires spares sprees spears spores sprues sprays speirs spiers sapphires suppress spurreys spurries spars spurs superrace speers spoors spruce sopors sapors sparse supers sippers soapers sappers suppers sapours saporous sparrows sporozoa spurious sprucy
spiraea speir spier spire spirea spiry spray supra aspire