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.
saguaro saggar sugar scaur square sugary soucar seggar sagger saggier scar scary sacra cigar scare scour sucre saker scarry scurry secure soaker sowcar sacker squire sucker scarey soggier suckier