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.
whoopies whoopees whoops whops woops weepies wops whaps whips whups wipes whaups wheeps whipsaw waps weeps
copies whoopies opes pies ropes weepies popsie whoopees topees dopes popes pappies nappies loupes lopes koppies chappies chippies yippies kewpies topis guppies hopes poppies hippies pipes tawpies spies puppies buppies hoopoes mopes copes coupes topes cowpies cheapies shoppes yuppies pes pis ops
whoop whoopee whoopie whop swoop swoopy wop