Some people are always late, but it’s hard to know how much contingency to build into your plans with them. I was thinking about some kind of app where if you are due to meet someone at X time, you’d press the button when they actually show up. Then over time you could build up a profile of their lateness. It could even aggregate people’s likelihood of being on time over lots of users. That way you could be meeting someone new and know to take a good book with you! It’d be pretty easy to do technically, but it’d be tough to get all the supporting pieces into play. You’d probably need to get the meeting time etc. from your calendar app (which most people don’t use for social things).

It might work best to quantify your own lateness. Some kind of training tool to make you a better, more on time person. Or it could feed data to google now so that it reminds you to leave to get somewhere Y minutes early.

Would you use it? I probably would.