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.
frump frumpy
rump crump grump trump frump grumpy warmup tromp tramp primp cramp gramp crimp frumpy romp ramp shrimp
farm fermi firm form forme formee forum frame from