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.
gas gays gaes goas gassy gauss gawsy kas gawsie gos guys case gaze caws koas kays kaes cays goys kaas casa keas goos goes goosy quays gussy quasi guess cause gauze guise gazoo goose gauzy quais quass cassia causey goosey gussie queasy