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.
tumor tumour tomorrow timer tamer dumber tamari tambur teemer timber timbre tamarao tambour tambura timbery tamboura
rumor humor tumor mor moor mora more amour femora fumer humour memoir memory remora rumour tumour