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.
trepid torpid tripod torpedo trapped tripody tripped trooped trouped trapt draped dripped drooped dropped trippet
trepid rapid repaid creeped creped groupoid prepaid torpid
tarp trap trip tripe trippy trop trope strep