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.
spud spued sped sapid spade spode spaed sputa spado siped spied spout speed sopped speedy sipped seeped souped speedo sapped soaped supped sept spat spit spot septa spait spate spite