Cube World, developed by Picorama, is billed as a voxel-based, randomly generated, action-adventure RPG with borderless worlds and infinite character progression. It's not exactly an MMO, but it's pretty darn close: It also has a crafting system, PvP combat, and cooperative play via LAN or the web. If that sounds like something you would enjoy, you're in luck: Cube World's paid alpha phase has officially begun.
Well, sort of. In order to get into the alpha, you'll need to pay for the game via the Picorama shop. In order to use the shop, you'll need to register. And thanks to what the developer claims are regular denial-of-service attacks, registrations are currently disabled. Foiled again.
In the meantime, you can get an extremely limited taste of the game's looks by checking out its mini demo.