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.
saporous sapors sapours spurious sprues spoors sopors spores soapers sappers sporozoa sparrows spurs spars sapphires supers speers spruce sprucy spiers sparse spires spears sprees cyprus spares speirs sippers suppers zappers spurreys spurries suppress sprays
porous vaporous saporous parous porose biparous viperous cupreous cuprous leprous spurious uprouse
sapor sapour sopor spoor spore