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.
groupie group grope croupe croppie gripe grape croup croupy grippe grapey gripey crappie creepie grip gorp crop carpi crape crepe cripe grapy gripy crepey grappa grippy