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.
naps knaps napas napes neaps nappas nappes nips nappies knops neeps nipas
baps naps cheaps whaps taps zaps saps wraps reaps raps paps neaps knaps haps maps leaps laps gaps caps heaps soaps daps waps chaps yaps
nap napa nape nappa nappe nappie nappy