MoCraft

MoCraft runs at mocraft.mc.gg and it's a straightforward Minecraft server to jump into if you already know the game. There's not much fluff around the address itself, so what you're getting is Minecraft as Minecraft, the sandbox building and survival game most people already know from Wikipedia's own entry on it. If you're looking for the full rundown on mechanics, versions, or how the game works before you connect, that Wikipedia page is a solid read. Otherwise, just plug the address in and see what the world looks like for yourself.