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.
copses capiases coppices capizes capsize gaposis
apses sepses woopses lapses copses supposes reposes speisses repousses lapises pisses reopposes psis capiases lupuses opuses dipsos lapsus sepsis biopsies poussies gipsies posies bypasses apsis apposes pussies puses upases diapauses gypsies possess pappooses deposes paseos speises poises eposes posses lipases poses appeases pusses tapises spouses dipsas passes pases peases peises opposes papooses popsies repasses repossess poesies pauses
copse cops scopes cups coypus coypous cowpies cowpeas coups coupes coppice copious copies copes copays coops caps kops scops