A small world, created using a preset. It has villages (size=3 & distance=20, which basically means they're larger than default and much closer to eachother) and renders a purely Savanna-biome world. It has no mineshaft or dungeons, but decoration renders as usual (trees, flowers, ores, ...). Extending the world without problems only works with versions beginning at snapshot 13w36a.

Preset-code is 2;1x7,35x2,8x3,1x2;35;village(size=3,distance=20),decoration.
You can also let dungeons and strongholds spawn by extending the preset-code to2;1x7,35x2,8x3,1x2;35;village(size=3,distance=20),decoration,stronghold,dungeon.

You can also set the number of strongholds and their spread around spawn.
f.e stronghold(chance=20,count=5,spread=5).
This makes the world create 5 strongholds, with a chance of 20 (higher than default, about 12 more) of spawning within 3000 blocks of spawn, much further out than normally.

Fo more information on how to use presets and create some interesting flatland-type worlds, see the Minecraft wiki :)