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.
sigher siver sphery sypher sphere cipher savvier safer saver sever cypher savior severe soever suaver suffer saviour
higher cougher laugher nigher rougher sigher tougher weigher gopher cipher cypher sphere sphery sypher