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.
trapper tripper trippier draper drapery dripper dropper trooper trouper drippier dorper torpor droopier
wrapper trapper crapper rapper crappier warper grippier tripper drippier grapier dropper crupper dripper cropper draper ripper grapery harper reappear reaper rapier raper gripper preppier frippery drapery trippier carper sharper