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.
lupus lupous loups loupes laps lips lops lapis lapse leaps loops lopes lipase
lupus pupus ups pus pappous soups coypus supes quippus dupes cups quips taupes upas loups tups whaups yaups quipus pupas loupes dups coypous jupes jaups puss opus pappus pups coups lupous roups spues sups coupes whups yups