One of my favorite cool treats is homemade ice pops. They can be made with any fruit juice you have in your fridge (they take about 4-6 hours to freeze completely) or you can get a little fancier (and more sophisticated) with combos like coffee with vanilla ice cream, or mojito flavored pops for the adults. These are also great for that peach or watermelon that is a little mealy or not so sweet. You can just put your fruit into the ice pop mold and then fill it with fruit juice. The juice will increase the sweetness of the fruit and the mealy texture disappears when the fruit is frozen.
Ice pop molds also make a great summer housewarming or birthday gift. They cost about $5-$15 and can be purchased at stores like Bed Bath & Beyond or Williams Sonoma. An added nice touch is to gift them with the pops already made. I recently gave this set as a "Thank You" gift to some friends who were extremely helpful when our second baby was born. These pops were made with homemade lemonade and organic strawberries. I will post the lemonade recipe shortly.
For a more substantial gift, you can also include an ice pop recipe book. Here is one I recently bought for my parents from our favorite bookstore in Vermont, the Northshire Book Store. If you are ever in Manchester, VT you should definitely stop by.