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.
density tensity dynasty tenacity dynast dunnest tennist tonicity downside teeniest downiest deionized tanist tensed tannest tiniest toniest
tensity density nasty venosity vinosity honesty lanosity mainstay nonsuit hyponasty sinuosity sunsuit dynasty
dens deans denes denies dense donsie