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.
riper ripper raper roper rapier rapper reaper ropery ropier roupier wrapper reappear repro repair repour rapparee
piper viper wiper riper per quippier bopper heaper reaper copier popper gappier papery knapper moper hooper goopier cuppier lopper pepper mopier copper pauper opera lipper japer caper roper appear nippier peppier looper soaper spier coappear spear gipper gaper nipper ropery ropier tipper supper toper doper typier zippier deeper whapper whippier whopper cheaper shaper shopper yauper taper chopper dipper chipper hopper soapier leaper speer soupier sappier apery weeper zappier wrapper loper sipper happier duper kipper foppery reappear keeper aper hyper napery mopper ripper capper rapier japery coper pappier hoppier loopier cooper gawper popery raper napper roupier mopery quipper hippier hipper pear beeper paper lippier lapper mapper peri pere peppery loppier pier coopery coppery pipier zapper diaper dippier sapper gypper leper dupery weepier hoper rapper speir cupper soppier peeper seepier peer hepper super whipper shipper chippier cheeper dopier nappier dapper whooper choppier tapper upper zipper topper tippier yapper yawper
ripe rip tripe rape rope ropey rupee cripe grip gripey gripe grippe grippy gripy drip drippy trip trippy