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.
goops coops kops gaps cops gawps gapes coups copse copes coypus coupes copays copies koppas cowpeas cowpies coypous guppies koppies copious caps cups keps kips
hoops poops loops oops woops coops whoops goops ops bops hoopoos roups popsy fops loups soaps soups poohs knops hopes poos popes lopes mopes cops topos dopes chops papoose biopsy opes hyssops opus lops sops dopas hops copes ropes topis topes copse tops pops kops pappoose coups mops wops whops shops