Great for sneeking your own liquor into bars and restaurants. Be the cheap person that I am, I tried my best to sneak in pint bottles so I would not have to pay the premium for my mixed drinks. This however go fairly unattractive in the summer trying to lug a pint bottle in my shorts or jeans.
My idea would be to packetized liquor (obviously not in sizes greater than shot) in a dissolving capsule that would release the liquor when it touches your mixing beverage of choice.
Reward: Some recgonition and some free samples