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.
croaker croakier cracker crooker creakier crockery crookery corker corkier craggier caracara groggery groggier quirkier
croaker breaker worker darker parker larker crooker raker cracker corker phreaker freakier forker broker brakier racker barracker barker wreaker rookier rookery rocker creakier croakier crookery marker porker tracker sharker
croaky croak crack cracky crake creak creaky crock crook