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.
operas operose oppress
copperas operas jeepers loppers gyppers prays pipers apers proas hoppers capoeiras vipers cuppers beepers coppers coprahs hoopers praus prase lappers lepers nippers peres peepers copperahs copers knappers gawpers soapers papers weepers yaupers spireas shoppers shapers tapers chippers wipers diapers whoopers whippers zappers toppers appears speers tippers reappears dopers rappers sappers aporias rapers ropers supers mopers spiers loopers kippers coappears keepers perse coppras copiers paupers boppers leapers pears paras gippers piers quippers capers sippers praos copras lippers japers coopers heapers mappers peppers nappers gapers apyrase cappers hopers hypers peers spears speirs peris sprays rippers poppers lopers wrappers rapiers dippers reapers tappers moppers uppers topers suppers whappers whiprays zippers whoppers cheepers dupers choppers shippers spiraeas yappers yawpers