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.
petard petered putrid pattered pottered powdered puttered patriot
leotard petard ritard retard dotard tart tetrad tardo start tared nitrid trod putrid turd teared dared hatred hotrod metred mitred stared tardy trad chytrid
peatier peter petter pettier pewter poetry