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.
frock fork frog forgo forky freak ferric forego freaky froggy farrago frag frig frug
rock frock crock brock trock roc wreck croak reck broke rick croc ruck brook crack arrack rocky rook derrick drouk taroc track troak troke carack crook hayrack grok euroky wrack iroko barrack carrack brick prick rack crick wrick cruck heroic rerack dreck duroc tarok trick hayrick truck