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.
rigour rigor rigger roguery recur regrew regrow rocker rugger reekier require rockery rockier rookery rookier
vigour rigour gor agora gaur goer gore gory guar guru leaguer augur augury vaguer vigor voguer jaguar ligure rigor figure muggur scour
rig brig ergo frig grig prig trig trigo