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.
tuffs toffs tiffs duffs teffs tufas taffies taffias toffees toffies tofus daffs doffs diffs dufus toughs tafias tophus typhus dieoffs diffuse typhous taphouse toughies difs tavs
huffs duffs pouffs guffs muffs cuffs puffs chuffs ruffs buffs tuffs luffs howffs caffs dieoffs naffs biffs jiffs boffos poufs dufus teffs gaffs offs piaffes coiffes ruffes diffs miffs chaffs waffs riffs boffs baffs quaffs effs daffs bouffes feoffs quiffs cuifs gaffes doffs tufas buffos raffs pouffes kufis coffs toffs whiffs luffas chufas tiffs yaffs
tuff duff taffia taffy teff tiff toff toffee toffy tufa stuff stuffy