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.
whoopees whoopies whoops whops woops wheeps wops weeps whaps whips whups wipes whaups weepies whipsaw waps
topees whoopees opes pees whoopies toupees coupes epees veepees hoopoes hopes copes copies topes loupes teepees mopes peeps popes ropes dopes tepees rappees rupees lopes shoppes pes ops
whoop whoopee whoopie whop swoop swoopy wop