One flavor I really want is agua de jamaica, another popular mexican drink. Come on Eric, you nailed Horchata I have faith you will make an awesome Jamaica!!!!
On the other hand there are several Asian drinks I love that would suit well for the sweet fruity shisha loving people. Drinks like: Ramune, Milkis, a rice punch called Shikhe, and of course the best of all THIS:
[img]http://tokyo5.files.wordpress.com/2009/06/cucumber-pepsi.jpg[/img]
P.S. Im totally lying about the last one, but its not THAT bad, tried it when I visited Japan. It's like eating hot dogs bathed in maple syrup. It wouldn't taste THAT bad but you'll probably get sick.