Cheap, tasty, and useful.
These things are great. They keep you hydrated, add some flavor to your water, and they are super portable. Drop one in a water bottle, or 2 in a hydration pack, and you are good to go. Just don't drop the nuun and seal your drinking vessel right away, as it fizzes pretty strongly. Also, if you are into hydrating yourself as you dehydrate yourself, the lemon/lime flavor mixes pretty well in a ghetto G&T for post-activity celebration.