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.
shredder shrewder shorter shirtier charioteer charter
redder shredder treader tireder prodder gridder greedier cruddier breeder herder ruddier rudder ridder reedier redear reader shrewder
shred shard shared sherd shored shrewd shrewdie