I found an awesome world seed earlier today, when you spawn it is rather bland, a plains biome, and a small cave next to where you spawn. However when you step into that cave, it is ore heaven. In the first room is an abundance of iron and coal, and it leads to a GIGANTIC cave system that has 8 diamonds not too far into the cave system. As I explored this cave system I noticed a large amount of gold, iron, redstone, and even some deposits of Lapis Lazuli. When I dug my way out, I found myself in front of a mountain that has a large amount of tunnels in the side of it. All in all, once you explore the terrain around the spawn you will understand why I had to post this. If you would like me to leave the seed, please leave a comment saying so and I will respond to your comment with the seed.