Minecraft – How to draw the attention of (“ping”) other Minecraft players to a specific point in space

In multiplayer Minecraft play, is there a way to visually draw the attention of other players to a point in the world? Much like the "ping tool" in Portal 2, or to a lesser extent, the minimap ping in Starcraft.

I am mostly interested in using this in creative mode, especially when all players are already nearby and I want to direct their attention to a single spot in a room. I am using a Bukkit server, so answers that relate to that are also acceptable.

If it's not clear, the Portal 2 ping tool looks like this: . There's an animation that is visible no matter where the player is looking (even away from the target, even on the other side of a wall), and then it focuses in on the point of interest.