Dead Sea and Salton Sea leap to mind as good projects.

Also could we store more water in the atmosphere? If we just poured water into a desert like the Sahara, most of it would evaporate before it flowed back to the sea. This would seem to raise the average moisture content of the atmosphere. Sure eventually it gets rained back down, but this would seem to be a feature more than a bug for a world that keeps looking for more fresh water. Indeed my mind is currently inventing interesting methods for moving the water around using purely the heat from the sun as an energy source.