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.
merch march mariachi marsh marish marshy moorish
merch perch church torch diarchy preach breach larch reechy retch rich wretch arch reecho reach march brach caroch carroch creche curch currach lurch birch parch breech orach porch search dreich torchy churchy