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.
whiffer wafer wiver wafery waiver wavier woofer weigher whoever waver wavery weaver weever
niffer differ whiffer deffer lifer daffier suffer puffier puffer goffer liefer quaffer offer doffer reoffer buffer zaffer chaffier chauffeur chuffer knifer deifier buffier feoffer fifer heifer gauffer gaffer duffer coffer iffier coiffeur huffier rifer miffier piaffer puffery reifier chaffer chauffer chiefer chuffier fer