I recall seeing a recipe that used some kind of bitters in (or perhaps as?) an ice-cream topping. Rhubarb bitters on vanilla ice-cream seems to me like it would be a great combination.
And GotGarlic - I am a big gin-and-tonic fan, but putting coffee flavor in it sounds like the craziest thing in the world to me. I'll have to try it! I make my drinks fairly heavy on the lime; would you recommend cutting down on the lime (or dispensing with it entirely) when using the coffee bitters? Would you mind sharing what recipe/proportions you use when you mix yours?