I have mentioned in some of my posts before, when you replace vodka with dark rum in cocktails in which coffee and vodka are used together, the cocktail becomes much more enjoyable. There may be exceptions, but I think you should definitely try espresso martini with dark rum. An espresso machine is a must for a good espresso martini, but if you don't have it, you can try different alternatives and you will still have a good drink. I also enjoy addition of different flavors like the chocolate and cherry in this one.