I've recently been playing Minecraft on 2b2t.org. The server has a regular lag which can be very annoying when you are starting out. In chat the other day, a player commented that he loved the lag saying it was 'part of the experience'. I started thinking about that and realized that the lag, if you assume it is always present, can be used as a tool. If you know lag is coming, you can do things that you know will be 'unwound' over the next X many seconds. That means you could fall into a hole and see what's in there, then when you lag warp back to where you were, decide not to go into the hole because there was nothing in it of interest.
Imagine if we had that ability here.