It would be interesting to know how many questions are asked every day, understand how this number behaves over time and versus the number of visitors/users.
For example: is the "rate" of questions linear in the number of visitors? Polynomial? Maybe it has stronger relation to the number of subscribed users and not to visitors. You know, some stats fun.
I think that exposing several simple numbers will allow the community to calculate these graphs and stats, and give back to the StackOverflow family of sites by pointing out interesting statistical insights.