This drink is merely a Greyhound with salt, but oh, what a difference it makes! Try it with some fancy culinary salts for a neat twist.
Salt the rum of your glass by wetting the outer edge with a bit of lime or grapefruit, and then gently roll it in a plate of salt. Be careful not to get salt on the top or inner edge of the glass; salty chunks in your drink is no bueno. Fill the glass with ice and build the drink in the order given.