If one wants to make a long stretch one could be appreciative of the UN by alleviating one of back issues by lessening the weight of ones pocket placed wallet.
Other than that I can't think of a positive coming out of the UN as a citizen of the USA.
"I'm trying to think of a single example of the UN doing something positive recently..."
Depending on your definition of "recently" the only thing I can think of is a book published by UNESCO in the early 60's on how to create an entire science lab with common household stuff--lightbulbs made into flasks, etc. I think it's been at LEAST that long since they did anything I'd consider positive.