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.
ireful irefully
ireful direful rueful careful dareful briefly weariful firefly tearful sorrowful carful refuel fearful jarful refly refel trayful earful cheerful