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.
pulper pulpier polypary polypore polyparia
helper gulper yelper pulper gulpier flapper sleepier leaper slapper floppier loper sloper flappier flipper eloper blooper bleeper lopper lapper walloper slippery clapper slipper leper sleeper pulpier caliper lippier galloper clipper calliper looper loppier flopper loopier slippier sloppier gloppier lipper
pulp pulpy palp palpi plop pullup