Seems like Minecraft beat me to it (again
I've been pondering for a few days now, that minecraft levels are really terribly stored (thousands of tiny files are really cumbersome, at least on Win).
So I thought MineServer could implement different world storage engines, from the current Beta-1.2-compatible to a monolithic-file or possibly even others. I'd especially very much like the monolithic file, that would be really great for transporting a world between computers or for backup.