Yet another game on the "Glacier" seed. Again, most stuff is underground, including a vertical mineshaft from the top of a mountain (level 120) to bedrock (level 6). Minecart system connecting all mining complexes.
Update: Built several more mineshafts and connected them to the minecart network with a new station type of my own design. Completed the 1-to-1 scale model of my real-world house. Hollowed out a giant floating boulder to be future living space. And built a gigantic Union Jack out of 1500 dyed wool, all of it legit.
Update Aug 23 2011: Built a couple more mineshafts and extended the minecart network. Now have both ends linked both by minecart and by nether-gate shortcut through a protected underground tunnel in the Nether. If anyone wants to finally get that "On a Rail" achievement, just download this world and ride a cart from either end of the track to the other, it's 1.2km long already.
Update Sept 12 2011: Completed partial loop back of minecart track, three more mineshaft stations. Looking for pathway for new track line to create full loop. Getting a bit sick of dying in lava.