A Hacker News Post Got Us 30x Visitors: Numbers & Lessons Learned

I did a similar study of traffic solely attributable to a single post on ReadWriteWeb. I wrote a technical paper with the results: http://www.stinkyteddy.com/documents/SocialMediaResponse.pdf The long tail traffic is well described by an exponential function with a "half life" of about 10 days. You should check your data to see if that number is universal.

You serve all you content via HTTPS? Including most static files/images, even though you have some non HTTPS objects which are not encrypted (and the browser notifies users of this).

Perhaps there is some business reason you have for this but it seems like a lot of wasted cycles.

That is a very small amount of traffic to experience issues with. If you want to inform about how much load was put on your systems, you should show pageviews and also show/look at stats on the static content (if you are using one server to serve it all).