Buy the deserts
There's a lot of crap land in the world. Many millions of square miles of sand, dust, toxic waste, landfill, impassable cliffs, gulches and swamps.
Governments will sell us this crap land for pennies a square mile. Heck, they'll be delighted to see some return on it. No one can live there, you can't mine it, you can't grow anything on it - it's useless.
Now nanotech is just a decade or two away. Nanotech can reshape the crap land into millions of acres of wonderful raw materials - gardens, farms, mines, chemical feedstock, all the things people might want. Just not yet.
So we Buy the deserts and then start trading futures on them. At first these futures might be worth no more than the pennies we paid for the land. But as the tech starts getting real those pennies are going to turn into dimes. Then dollars. Then real money.
Plus the crap land is ours to map however we want. We can use zoning and planning to literally write messages on the maps. Click "Hybrid" on google maps view of the sahara and you'll see your corporate logo inscribed in letters 100 miles wide ... that's gotta be worth something to someone.
Anyway as the futures begin to appreciate their owners will obviously start plowing profits back into developing the tech that will make the futures inflate. If you want to turn the deserts into gardens, really, all you gotta do is start parceling 'em up and selling 'em off ...
