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.
sopor sapor spore spoor soaper sapour soppier soupier spur spar soapier spry spear speer sprue spier spree spray spire super spiry supra speir spare sapper sipper sparry spurry supper spirea sappier seepier spiraea spurrey sapphire
sopor cooper toper spore hooper sapor repour moper loper looper copra coper hoper poori poor vapour vapory vapor pour pore roper sapour spoor doper whooper
sop sepoy soap soapy soppy soup soupy