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.
sapiens spins sapiency sapience spense spines sappiness soapiness supines spinous spinnies spans spinneys spoonies soppiness spawns speans spence spoons spinose spooneys cioppinos
sapiens pens pins peens lipins peons pippins papains opens lupines penes pains pians penis ripienos peans spense spins deepens cheapens chopins peins pinas reopens repines spines supines rapines pepinos speans repins pines cioppinos chopines tiepins ripens opines pions lupins lippens lapins copens happens shippens