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