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.
toughy tough toughie teugh tofu toph toffy tophe tophi
saughy toughy roughy ugh saugh lough tough teugh sugh sough pugh rough faugh laugh kiaugh cough vugh waugh
dough doughy boughed bought dought doughty tout