Lots of underground chambers, rail roads, mushroom collectors, piston works...

http://minestatus.net/10142-yugoslavia

Update 30.08.2011.
Update 25.09.2011. (v1.8)
Update 10.10.2011. (1st Village, and Stronghold)
Update 26.10.2011. (Water castle)
Update 27.11.2011. (2nd Stronghold, 2 additional Villages)
Update 19.12.2011. (found mushroom biome)
Update 06.02.2012. (many new additions to map, several unclaimed Villages)
Update 19.02.2012. (Added Spout support, build Roller Coaster)
Update 02.03.2012. (City is built!)
Update 17.04.2012. (Lots of new stuff)
Update 06.06.2012. (Periodical update)