I've been trying to find creative uses for Patrón XO (which is a coffee-flavored tequila, and which is also awesome, by the way, and I recommend it). I've poured it over vanilla ice cream (FTW) and also combined it with milk to make what I think may be a new cocktail.
I was inspired to add milk by the classic mixed drink, the White Russian, which you probably already know is vodka, Kahlua, and cream. There's actually an existing variant called the White Mexican that substitutes tequila for vodka, so no credit for discovering that, unfortunately. Patrón XO combines the tequila and the coffee liqueur into one potent potable, and I think that's just different enough to qualify as a different drink. Try it. Or not. It's a free country.
Have you ever tried a Grasshopper? I've only ever been to one cocktail bar that has it on the menu: The Wellesbourne on Pico in West LA. It's good, but it's more of a dessert cocktail, and they look at you funny if you actually order one. I was there on a date once and ordered it and I didn't get a second date and I wonder if that had anything to do with it. But I HAD to order it because it gave me an excuse to tell one of my favorite jokes. Which goes as such:
A grasshopper walks into a bar. The bartender says, "Hey, you know we have a drink named after you." And the grasshopper replies, "Really? You have a drink named Steve?"