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.
wispier waspier whisper whispery
spier waspier wispier raspier whisper gasper whispery jasper sappier aspire asper zippier zappier super spiry spire speir suspire speer soupier seepier vesper jaspery gossiper rasper spear lisper respire despair soppier soapier