A Robson Cocktail combines dark rum, orange juice, lemon juice and grenadine. My recipe comes from The New York Bartender's Guide. I have written before that rum doesn't usually compete well with citrus but it pops out nicely here.
Grenadine, originally produced from pomegranate juice, is now more often made with black currant and/or artificial flavoring. In mixology, it is used as much for coloring as for taste.