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.
crappie croppie crape crappy crap creepie carpi grape crepe cripe grapey grippe grappa croupe crepey groupie carp crop creep crepy croup grapy gripe grope creepy croupy gripey grippy
crappie rappee frappe croppie preppie sharpie