We were just discussing this today, that we needed rabbits for potions of leaping.

I second this. While we can build to our neighbor's island, as soon as we reach it, we can no longer place blocks. However, the block will be placed just long enough for us to step on it. We then plummet to our deaths before we can figure out whose island we visited. Furthermore, even though we can check the logs for the name, we might not remember it. A command would be helpful. That way, we could use the local chat more effectively.