Freeze lemon/limes or other fruit in muffin tin for flavored ice cubes. I think I would cut them in smaller chunks and use a mini muffin tin though.
DIY Flavored Extracts ~ Vanilla, mint, orange and lemon (Baking Sweet Dipping Sauces)
DIY lemonade station - Make your own lemonade bar. Great for a summer celebration; Blueberry mint, key limeade, raspberry lemonade (Cool Food For Kids)
How to make healthy flavored water. Love putting fruit in my water. Healthier than added packets of flavoring. Sooooo yummy and refreshing.