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.
cark carack cork carrack creek crick creak quark croak crook cargo corky crake crock crack cruck crikey croaky cracky creaky carioca crickey karaoke crag croc grok kirk greek quirk
ark bark hark cark quark lark mark nark park sark dark wark chark shark