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.
cacaos cacas cocos guacos caucus cuckoos cogs cokes cocks cooks cocas cakes kakas cocoas kaiaks quacks caiques cookeys cookies guaiacs quaggas cox
cacaos cos coys boocoos buckos ficoes fucose fucous cows cosy cocas cocos guacos makos locos mucous pacas raucous sagos sickos dagos decos dioicous wackos chicas shackos showcase mucosa casa geckos macaws cays caws case jockos jucos coss coos jocose cacas cocoas cogs locoes micas mucose ocas picas cycas scows socas decays decoys tacos whackos chicos shakos yucas
caca cacao caeca macaco macaque