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.
sparrows spars spares sparse spears spurious spurries saporous spurreys spurs sprees spores spoors sprays sprues spiers speers supers sapors sopors spires speirs suppers sappers sapours spireas sippers soapers spiraeas sporozoa suppress sapphires superrace spruce sprucy
sparrow sparry spar spare spear spurrey spurry