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.
croupier crepier grouper cropper crupper crappier creepier groper carper crapper gripier creeper grapier grippier griper corpora grapery gripper
croupier syrupier roupier sirupier grouper trouper grippier droopier gripier preppier larruper crappier grapier creepier ropier rapier drippier crupper trippier crepier chirpier
croup croupe croupy crop croppie group groupie