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.
pensil pensile pencil penicil pencel penicillia
pensil tonsil noisily tinsel nosily ensile hansel consol consul gunsel council counsel mainsail mensal moonsail pencil pensile tensile uneasily
pens pensee spence openness pons pans pansy peans peens peins pence penis penes pennies pennis peones peonies peons pins puns opens spense