Well, because of the lava bucket thing being added in 1.3 (which I am very excited about), I built a path to a lava ocean in the Nether. Here, you can access premium Nether lava for all your furnacing needs.



Here is the dirt arch that leads to the lava ocean. You can see it in the distance. This arch is near the sign for the Mushroom Island (as can be seen) and the Nether Fortress(?) sign.