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.
duff doff tuff daff diff daffy dieoff def dif defy toff teff deaf tiff tufa defi deify taffy toffy
buff huff cuff guff luff muff pouff puff ruff duff tuff chuff