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.
nappa napa nappe nappy nap nappie knap nape neap nipa nippy nip knop neep nope
kappa nappa app papaw chuppa papa zappy nappy pupa nappe pappy pappi koppa napa kapa gappy cuppa huppah happy poppa sappy tapa chuppah