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.
aspis asps auspice
cuspis aspis wasps despise rasps lisps hyssops saps sepias sips sops spas spies sups asps espies hasps cusps gasps gossips knosps sysops tossups wisps