Lapis, while not being common, is relatively easy to find - Just explore any deep, bountiful caves and you're bound to find a few blocks of the stuff.
Lava farming - Also shows how to create a smooth lava lake. My new castle will have a big moat of lava... But it'll take a little while, I think.
Oh, and it seems that if you build two portals in separate places, you'll teleport to the same portal in the Nether when you use either portal from "Earth", but re-entering the portal to "Earth" from the Nether always takes you back to the first portal that you made, not your second. Deactivating your first portal doesn't work - The game ends up making a new portal in a random location near your first portal rather than teleporting you back to your second portal (if that made sense). Kinda annoying.