This is a purely spleef server (with some free-building as well).
To join this server, go to http://www.minecraftforum.net/topic/339068-spleef-server-tournament-hosting-available/

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)

Just a picture and a map of the server that I run almost full time. Its mainly just for me and my friends but if you would like to join, just send me a message! We are always looking for new people to join our town or possibly build a new one. Tons of different areas to build in and lots of support if needed. It is also appreciated that if you decide to join our server, you have skype and a working microphone although it is not necessary ^^