Huh, this is actually pretty useful.
It does exactly what it says it does, and the seeds it generates (at least for me) have managed to get me near forests with already open caverns full of coal and ore. This allowed me to survive very easily (well, until I found 2 creeper mob spawners. Then I died horribly. XD)
All the same, as araphon1 suggested, you could put dropdowns into the flash that allow you to dictate quantities of things in the map like dungeons, caves, ores etc and possibly what you want the overlying theme of the world to be (I would go for something that gives pumpkins personally, jack o lanterns are awesome for light sources).
I've given you a 5/5 and a 10 star review. I hope you make another version of this with the amendments that araphon and I have suggested.