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.
spiers speirs speers spires supers spears soapers sippers spireas suppers sappers spurs spars spurries spiraeas sprays sprees sparse sapors sprues spares spoors sopors spores sapphires zippers zappers sapours saporous spurious spurreys suppress sparrows superrace spruce sprucy sporozoa
piers spiers rapiers copiers uppers moperies peeries cooperies dupers repairs papers pears suppers poppers loopers naperies nippers peers shoppers hoppers hoopers whoopers parries paries tippers copers vipers diapirs loppers gippers peres japers roperies yaupers shapers wipers whappers topiaries tapirs dopers zippers spurries speers soapers appears sapphires wrappers kippers cuppers copperas apiaries gyppers boppers gawpers moppers lepers lappers peepers pipers cappers chippers reapers capers sippers weepers spires perries spears dippers mopers keepers topers japeries aperies whoppers poperies peris mappers coopers operas lopers fopperies hypers paupers coappears perse gapers peppers beepers coppers heapers jeepers yappers reappears ropers choppers quippers leapers lippers pries hopers knappers rapers capoeiras pairs zappers tapers rappers shippers rippers sappers speirs nappers apers supers diapers duperies tappers toppers whippers cheepers yawpers
spier spear speer speir spiraea spire spirea spiry spree super asper aspire