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.
shudder shuddery shedder chudder shoddier shader shouter shutter chuddar shadier chider cheder sheeter cheddar chowder shooter shatter shittier cheddary shoetree chadar chador chadri chatter cheater chitter
judder chudder shudder budder udder rudder mudder bidder giddier kidder nodder louder faddier codder sadder rudery ruder doddery gaudery adder wedder chuddar shedder fodder badder shoddier tedder guider nuder padder ridder lauder gadder bedder ruddier dodder redder gaudier madder wadder widder odder muddier ladder shuddery