I would love to see a good interactive water resource go on the free for the month/permanently or made by epic themselves, I know way too many people who would love a good interactive water resource for their projects.
by this I mean water that
A. Has a ripple effects when you walk, drive, ride a boat in it
B. Has waves
C. (Optional) droplets that can interact with objects.
Basically less the water itself more so the interactively of the water
You could even team up with Nvidia themselves to create a resource.