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.
droops drops troops dropsy hydrops dorps drips hydropsy tropes drapes drupes troupes towropes traps trips tarps turps trapes tripes tripos traipse trappose trappous
droops troops groups roups corps crops croups gorps gropes ropes dropsy liriopes preops props pyropes dorps drops hydrops towropes hyperopes hydropsy tropes