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.
cripple gripple carpale grapple carpal carpel carpool crapola creepily croupily graupel
ripple cripple gripple ripply hirple grapple triple
crappie crappy cripe croppie grippe grippy scrip