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.
croak croaky crack crook crake creak crock cracky creaky carack carioca cark cork croc crag carrack curacoa grok cargo corky creek crick cruck craggy crikey crickey curacao karaoke grog kirk
croak troak crack berake phreak brook freak break braky arrack barrack traik carrack grok crock drake rake tarok crake trock brock brake iroko rack rook hayrack euroky frock raki raku rock broke wrack carack rerack crook drouk croaky track creak wreak arak troke