This has been a favourite in our household, and very refreshing especially in the hot afternoon. You can make several ice trays of your favourite juices, keep the cubes frozen in a zip lock bag, and have a couple of cubes to melt when you're thirsty.
The lemon juice iced cubes are my favourite. Juice 2 whole lemons, dilute with some water and add a little honey as sweetener, freeze them in 2 ice trays (if you have 2), pop them into a glass after a couple of hours, enjoy! The best thing is, lemon is a great antioxidant and helps reduce inflammation, which we all need to aid recovery after many tough workouts in the gym.