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.
speise specie speiss spaes spies supes sipes spews spues spouse suppose sops sips saps spas sups cepes space spicy spays spice soups soaps spacey spicey hyssops
peise speise paise pease poise appease kepis specie speiss
sepia sipe spae spew spue supe