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.
billowy billow blowy billy bellow bill blow belly bally bialy bully below bailey billie blooey bile ball boll blew bowl boil bail blaw bull bell bolo belay belle biali bluey bulla bylaw bailee bailie blooie boulle bullae
billowy willowy pillowy yellowy sallowy tallowy sallow yellow callow mallow allow lowly tallow pillow hollow follow hallow wallow fallow blowy billow alloy bellow willow fellow shallow mellow low