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.
grippier gripper gripier griper grapier crappier groper crupper grapery crepier cropper crapper grouper creepier croupier carper creeper
crappier trippier grippier preppier drippier reappear crapper trapper rapper droopier gripier ropier dripper sirupier creepier wrapper croupier ripper roupier crupper grapier frippery gripper rapier syrupier dropper crepier tripper cropper chirpier
grippe grippy grip grappa gripe gripey gripy