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.
smear smeary simar somber simmer seemer seamer summer samara sambar summery seamier summary cymar sambur sombre samurai semiraw zamarra zamarro
smear shmear mar gammier mammer namer comer jammier gummer lamber gamier rummier humeri gemmier mimbar foamer hammier rammer boomier cymar lumbar limber limmer nummary boomer vomer bummer rhymer camera seamer beamier omer yammer smeary tamer shimmery shammer maimer chimere chimer samara chamber wommera summery umber timber bomber roomier dumber rammier daymare dimmer ameer dammar roamer summary rimier ember emery mummer seemer simmer homer cummer comber hummer mair simar hemmer omber homier gammer mummery camber member tamari hammer mere foamier gummier roomer loamier mare emmer aimer fumier number amber rimer limier mammary gamer lamer sambar mimer lumber maar rummer mara seamier somber jammer damar cumber dimer dammer reamer shimmer gomer embar teemer timer summer womera woomera emeer chimar chimera rimmer chummier fumer doomier yummier
same seam seamy seme sima smew soma some sesame