Original purpose: Quenching your thirst.
Aha! Use: Cleaning lime deposits and iron stains inside the dishwasher. Pour a packet of lemonade Kool-Aid (the only flavor that works) into the detergent cup and run the (empty) dishwasher.
Reward: Citric acid in the mix wipes out stains; you don't have to.
I ran my dishwasher with a few dishes in it (too lazy to take them out first) and my glassware was sparkling...better than I have ever seen them and I just had 2 packets of Lemonade Kool-Aid in it. I am impresssed!!