Exponential Trends – What Are Your Favorites?

Over at Hacker News there was a discussion about our ebay genome story that I thought was cool enough to post below.  In the first part of the thread user davidmathers is talking about the cost to sequence an entire human genome (which we have written about many times).  As user Femur later points out, there are obviously many such trends, which of course is a foundational aspect of Kurzweil's works.  Do you know of similar trends that are your favorites?  Let us know in the comments.  Just to break the ice, I will go first.  Check the comments!