Hydropolis, the Underwater Hotels to be built in Dubai, and the Islands in Dubia

They have not broken ground, but so many other amazing things have been done in Dubai, it probably will happen within a couple of years.
Check out Hydropolis

Check out The Palms Site
Along the same lines are the Palms: Jumeria-Done people living there,

Jebel Ali-Almost done,

and Deira-just started.
Check out The Palms Site

As well as The World--Islands done, handed over to owners to develop. Check out The World Video.
You can also use Google Maps or Google Earth to zoom down and look at the islands for real.