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.
gags gawks quags gogos kagus guacos quaggas guaiacs gawkies kegs cogs cocas gooks gowks gucks kakas kakis cacas cakes
ags mags shags tags dags zags sags rags peags nags lags bags quags gags jags hags fags wags yags