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.
flashier flasher fleshier flesher flusher foolisher filcher fletcher
fleshier sloshier slushier flashier plushier plashier plasher blotchier clasher polisher lasher leachier lusher flasher blusher flesher plusher foolisher slasher glitchier slouchier flusher welsher
flash flashy flesh fleshy flush