I like to use Torani or DaVinci Sugar Free Syrups to make flavored ice. I fill ice cube trays (half full) with the different flavored syrups. I then use the flavored ice cubes in my water. This is a nice variation from always using lemons or limes to flavor my water.
In the summertime, I like to freeze different varieties of fresh, seedless grapes. Then I use them as ice in my water. Frozen grapes also make a very crisp, refreshing snack on a hot summer day.