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.
dietary dieter datary deter tidier dotier tawdry deader detour deodar doddery deedier dottier deodara dowdier tetri tater titer dater tetra tatar doughtier doter datura dodder dotter tatter tauter tedder teeter tetter titter tattier tottery tuatara
dietary deary tarry teary betray votary notary poetry retear retry rotary cedary starry datary tar try