Right now I'm drinking a gin and tonic. Bombay Saphire, lime tonic (since we forgot to pick up fresh limes) and a few fresh leaves of basil. Yes, basil. Makes a great addition to a simple G&T. Mint is a good addition too.
Here's something delicious that my wife Allisonn came up with or saw somewhere:
She took half a personal-sized watermelon, and cubed it. Then half a pint of strawberries, and quartered them. 10 or so fresh leaves of basil and a few leaves of fresh mint. Bruised the basil and mint, and added it, the melon, and the berries into a 1 liter pitcher. Poured it 3/4 of the way full with gin and added (I think) 2 tablespoons of simple sugar syrup.
Let the mixture sit for 6 hours minimum, but overnight and half a day works best it seems...we then mixed it with lime seltzer. I mixed mine with lime tonic. You can strain the fruit and leaves out before pouring, or leave them in.
Either way, it's a delicious and refreshing summer cocktail.
Cheers!