Aside from the Rusty Nail, there aren't a lot of uses for Drambuie. So if you've got a bottle sitting on your shelf, this margarita variation is worth a try. The Drambuie lends a light honey flavor and a smooth mouthfeel, which is quite nice.
.5oz Drambuie
.5oz Grand Mariner
1oz Lime Juice
Rim a glass with salt, using a lime wedge to wet the rim. Shake the ingredients over ice and pour into salted glass with fresh ice. Garnish with lime wedge.