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.
toughs toughies tophs tofus tophes tophus typhous taphouse toffs tufas tuffs doughface doofus typhus devious toffees toffies typhose doghouse
vughs sughs coughs saughs laughs loughs ughs kiaughs roughs soughs toughs highs weighs quaighs ghis laighs aghas sighs ouphs nighs neighs yoghs
tough toughie toughy teugh tofu etouffee