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.
weepier weeper whippier wiper whapper whipper whooper whopper whipray
seepier weepier pier peppier sappier goopier keeper quippier leper reaper leaper mopier pipier nippier loopier soapier soupier zappier deeper dopier typier gappier hoppier cheaper chippier peeper piper ropier pappier pepper roupier hepper heaper happier lippier loppier beeper copier repair rapier hippier nappier cuppier soppier spier zippier dippier tippier weeper whippier cheeper choppier per
weepie weep weepy wheep sweep sweepy