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.
frisk frisky forsake forsook fresco pharisaic
risk brisk frisk risky rusk brusk frisky torsk
frise frisee ferias firs fraise frass fries frieze friz frizz frizzy furies furioso furious furs