I've always wanted to create big maps. Stuff that can be used to create whole worlds. Big maps are definitely possible with the "Generated Worlds" (working title) application. Below you'll see an example of four different maps created by the same random seed. The difference in each map is an "offset" factor that determines how final noise is generated. An offset of 0 (default) creates the first image, while an offset of (1 * Map height) creates the second, (2 * Map height) creates the third, and so on. The example below shows the "Height Offset" or Y-Offset. Of course the same is possible horizontally, allowing you to create huge maps consisting of N * N smaller maps.
There are a couple of tasks left before this works flawlessly, and that is to make sure rivers do not start at the edge of maps, - and to make sure texture heightmaps (for example forests) also overlap seamlessly into a large map. Luckily, the little detour into creating starfields has presented a nice elegant solution for the heightmap challenge already (although not shown here).
I think this is pretty cool, and I hope you do too!