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.
gasper gaspereau gossiper gossipper gossipry
asper whisper rasper lisper gasper jasper vesper super waspier sapper zippier spear soppier seepier raspier spar spier spur spry zipper whispery gossipper douzeper zapper disappear sappier gossiper speir supper zappier sipper jaspery peasouper soapier misshaper speer soupier soaper wispier