Slate is a nicely terraformed sim with a Linden-owned river valley going through it. At its beginning, it was at the end of the world, so the river ran into the infinite ocean. It also allowed for very remote builds.
Lordfly Digeridoo came into Slate around July 24th on his third day in-world. There was already a very nicely-done residential community in it, and suprisingly there was land on a flatly-terraformed hill right next to the river. That was his first home.
The great thing about Slate in those days was the total lack of commercialism. Each person that had land in Slate was there just to have a house; not only that, but a "natrual" looking house. Many folks had treehouses (Ananda Sandgrain, for one, as well as Ezhar Fairlight's perpetually unfinished megatree), log cabins (Bob Bunderfeld's amazing log cabin house that took up hundreds of prims), and other wood-and-stone constructions. As a newbie, Lordfly tried conforming to the unwritten "rules" of the sim by building a wooden home. The theme was bent a bit as he constructed a physical trebuchet on top of it (free rides for anyone who wanted it :)
As time went on other builds came up (Kenzington Fairlight's huge stone castle-type thing across the river from Lordfly, for one), some came down (some sort of library half-decayed), and others mostly stayed. :)
Ezhar Fairlight eventually made a small park and a wooden bridge that crossed the river at it's thinnest point, and Lordfly made a clocktower with his help not far away.
Eventually, most of the old folks moved out and a new bunch of people came in... the river valley is still there, though.
Slate also shared the Slate/Teal Amphitheater, which has since been deleted.
Note: Most of this account of Slate's history by Lordfly Digeridoo.