This is a bit of a nit-pick, but I don't let my students get away with this, so it seems worth mentioning. In the reputation section of a user's page it might say something like:

• Reputation
• top 0.90% this year

It seems that in the last line, either the decimal point or the percentage sign should be removed, since I don't think that this indicates that the user is in the top 9/1000 of users for the year. (Well, they are, but that's a rather poor lower bound!)