As soon as the price and shipping come down, I'm getting one of these!
Having studied fluid dynamics for many years in an Earth and planetary science context, can't tell you how much this demo tickles my fancy. Atmospheres, oceans, and even Earth's "solid" mantle all flow on their own time scales. The evolving flow structures are shaped by planetary spins and the 3D spherical geometry. (Think Jupiter's banded cloud deck and persistent storms.)
This gizmo, with its spinning fluid reservoir in the shape of a spherical cap, lets you play with some of these highly counter-intuitive processes.