Oblivion forests ain't got nothing on this. It bothers me somewhat that all my 2nd-rate attempts at artsy landscape photography are being decimated by French landscape imageing app called Terragen... now if only they could get these renders into games. Granted, such games would require a considerable investment in hardware to be able to run, but they'd negate the need to go outside be a special kind of awesome ^_^

Terragen

Edit: It seems this sort of thing isnt too far off; Enemy Territory: Quake Wars is currently flaunting something called 'mega texture technology'

"...MegaGen can automatically distribute materials such as grass, sand and rocks across the landscape, based on altitudes and the angles of incline. MegaGen makes moss grow up the steeper slopes and cling to rocks, grass grow in the flatter areas, and sand and snow gather appropriately in the crevices between rocks... All of this is compiled into a five gigabyte source texture..."

Makes those 750gig HDD's look almost necesary :(

Interview with ET:QW designer Paul Wedgewood