MobArena V1.0 out! check it out here: http://www.planetminecraft.com/project/mobarena-v10-the-ultimate-arena-expierience-for-sp-and-smp-withouth-any-mods-or-plugins/

This is a project I am building on for Minecraft 1.2+. It is a fully configurable mob arena, with several waves. At the moment you will not get any rewards and I should think about a better spawn algorythm =) The system itself works fully with the features there are in it at the moment, I am planning to add fully configuable waves, rewards,..

Map download:
http://www.2shared.com/file/nNk8aZ2V/MobArena_V01.html
ATTENTION: this arena needs mobs being able to spawn with dispensers. This is currently only available in the 1.2 snapshots. I hope MC updates soon, but in the mean time you'll have to download the snapshot version here: http://assets.minecraft.net/12w04a/minecraft.jar
(http://www.minecraftwiki.net/wiki/Version_history/Development_versions#12w04a)
navigate to: %appdata%/.minecraft/bin and replace the minecraft.jar file with the downloaded one. the map has to be unpacked in %appdata%/.mincraft/saves.
Feedback: I would really apprieciate any feedback here in the comments. If you liked this map, leaving a diamond will make others to find it and enjoy too =)

Have fun!
Zipron

Additional Notes

I'm not sure if the schematic will work. I know it get's bugged when you open it in an MCEdit version wich doesn't support 1.1/1.2 (and at the moment, there is no version for 1.1/1.2 I think). You can just laod the schematic with worldedit into your world =)